From 2959921349ec0178a96de624aa62e14a2705edae Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Wed, 25 Feb 2026 08:03:56 -0500
Subject: [PATCH 01/18] feat: add zstd

---
 fixtures/geotiff-test-data                 |  2 +-
 packages/geotiff/package.json              |  1 +
 packages/geotiff/src/codecs/zstd.ts        |  9 ++++++
 packages/geotiff/src/decode.ts             | 12 ++-----
 packages/geotiff/tests/decode.test.ts      | 37 ++++++++++++++++++++++
 packages/geotiff/tests/integration.test.ts |  4 +--
 pnpm-lock.yaml                             |  8 +++++
 7 files changed, 61 insertions(+), 12 deletions(-)
 create mode 100644 packages/geotiff/src/codecs/zstd.ts

diff --git a/fixtures/geotiff-test-data b/fixtures/geotiff-test-data
index 4f268831..811e37e9 160000
--- a/fixtures/geotiff-test-data
+++ b/fixtures/geotiff-test-data
@@ -1 +1 @@
-Subproject commit 4f2688310cbd9fccdd1c677ed8057b829ce99cb2
+Subproject commit 811e37e9b1f455aa58d3398456a99f8859f7be72
diff --git a/packages/geotiff/package.json b/packages/geotiff/package.json
index c1989468..7f87c5b5 100644
--- a/packages/geotiff/package.json
+++ b/packages/geotiff/package.json
@@ -55,6 +55,7 @@
     "@developmentseed/affine": "workspace:^",
     "@developmentseed/lzw-tiff-decoder": "^0.2.2",
     "@developmentseed/morecantile": "workspace:^",
+    "fzstd": "^0.1.1",
     "uuid": "^13.0.0"
   }
 }
diff --git a/packages/geotiff/src/codecs/zstd.ts b/packages/geotiff/src/codecs/zstd.ts
new file mode 100644
index 00000000..75b73f27
--- /dev/null
+++ b/packages/geotiff/src/codecs/zstd.ts
@@ -0,0 +1,9 @@
+import { decompress } from "fzstd";
+
+export async function decode(bytes: ArrayBuffer): Promise<ArrayBuffer> {
+  const result = decompress(new Uint8Array(bytes));
+  return result.buffer.slice(
+    result.byteOffset,
+    result.byteOffset + result.byteLength,
+  ) as ArrayBuffer;
+}
diff --git a/packages/geotiff/src/decode.ts b/packages/geotiff/src/decode.ts
index c92a1493..41a06837 100644
--- a/packages/geotiff/src/decode.ts
+++ b/packages/geotiff/src/decode.ts
@@ -46,15 +46,9 @@ registry.set(Compression.DeflateOther, () =>
 registry.set(Compression.Lzw, () =>
   import("./codecs/lzw.js").then((m) => m.decode),
 );
-// registry.set(Compression.Zstd, () =>
-//   import("../codecs/zstd.js").then((m) => m.decode),
-// );
-// registry.set(Compression.Lzma, () =>
-//   import("../codecs/lzma.js").then((m) => m.decode),
-// );
-// registry.set(Compression.Jp2000, () =>
-//   import("../codecs/jp2000.js").then((m) => m.decode),
-// );
+registry.set(Compression.Zstd, () =>
+  import("./codecs/zstd.js").then((m) => m.decode),
+);
 registry.set(Compression.Jpeg, () => Promise.resolve(decodeViaCanvas));
 registry.set(Compression.Jpeg6, () => Promise.resolve(decodeViaCanvas));
 registry.set(Compression.Webp, () => Promise.resolve(decodeViaCanvas));
diff --git a/packages/geotiff/tests/decode.test.ts b/packages/geotiff/tests/decode.test.ts
index 8d62d635..6cb3e024 100644
--- a/packages/geotiff/tests/decode.test.ts
+++ b/packages/geotiff/tests/decode.test.ts
@@ -1,3 +1,4 @@
+import { PlanarConfiguration } from "@cogeotiff/core";
 import { describe, expect, it } from "vitest";
 import { decode } from "../src/decode.js";
 import { loadGeoTIFF } from "./helpers.js";
@@ -38,6 +39,42 @@ describe("decode", () => {
     }
   });
 
+  it("can decompress zstd-compressed tile data", async () => {
+    const tiff = await loadGeoTIFF("int8_3band_zstd_block64", "rasterio");
+    const image = tiff.tiff.images[0]!;
+    const tile = await image.getTile(0, 0);
+    expect(tile).not.toBeNull();
+
+    const { bitsPerSample, sampleFormat, predictor, planarConfiguration } =
+      tiff.cachedTags;
+    const { width, height } = image.tileSize;
+
+    // This fixture is band-separate, so each raw tile contains a single band.
+    const tileSamplesPerPixel =
+      planarConfiguration === PlanarConfiguration.Separate
+        ? 1
+        : tiff.cachedTags.samplesPerPixel;
+
+    const result = await decode(tile!.bytes, tile!.compression, {
+      sampleFormat: sampleFormat[0]!,
+      bitsPerSample: bitsPerSample[0]!,
+      samplesPerPixel: tileSamplesPerPixel,
+      width,
+      height,
+      predictor,
+      planarConfiguration,
+    });
+
+    const bytesPerSample = bitsPerSample[0]! / 8;
+    const expectedBytes = width * height * tileSamplesPerPixel * bytesPerSample;
+
+    expect(result.layout).toBe("pixel-interleaved");
+    if (result.layout === "pixel-interleaved") {
+      expect(result.data).toBeInstanceOf(Int8Array);
+      expect(result.data.byteLength).toBe(expectedBytes);
+    }
+  });
+
   it("can decompress lerc-compressed tile data", async () => {
     const tiff = await loadGeoTIFF("float32_1band_lerc_block32", "rasterio");
     const image = tiff.tiff.images[0]!;
diff --git a/packages/geotiff/tests/integration.test.ts b/packages/geotiff/tests/integration.test.ts
index 5cbf91b9..7e186bbd 100644
--- a/packages/geotiff/tests/integration.test.ts
+++ b/packages/geotiff/tests/integration.test.ts
@@ -5,8 +5,8 @@
  * JavaScript, so we use it as a ground truth for pixel values, dimensions, and
  * georeferencing.
  *
- * Fixtures that require unsupported codecs (WebP, JPEG, LZW, LZMA, JXL,
- * zstd) are intentionally omitted here.
+ * Fixtures that require unsupported codecs (WebP, JPEG, LZW, LZMA, JXL)
+ * or band-separate planar configuration are intentionally omitted here.
  */
 
 import type { GeoTIFFImage, GeoTIFF as GeotiffJs } from "geotiff";
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index c62c2090..8ef758a6 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -406,6 +406,9 @@ importers:
       '@developmentseed/morecantile':
         specifier: workspace:^
         version: link:../morecantile
+      fzstd:
+        specifier: ^0.1.1
+        version: 0.1.1
       uuid:
         specifier: ^13.0.0
         version: 13.0.0
@@ -1798,6 +1801,9 @@ packages:
     engines: {node: ^8.16.0 || ^10.6.0 || >=11.0.0}
     os: [darwin]
 
+  fzstd@0.1.1:
+    resolution: {integrity: sha512-dkuVSOKKwh3eas5VkJy1AW1vFpet8TA/fGmVA5krThl8YcOVE/8ZIoEA1+U1vEn5ckxxhLirSdY837azmbaNHA==}
+
   gensync@1.0.0-beta.2:
     resolution: {integrity: sha512-3hN7NaskYvMDLQY55gnW3NQ+mesEAepTqlg+VEbj7zzqEMBVNhzcGYYeqFo/TlYz6eQiFcp1HcsCZO+nGgS8zg==}
     engines: {node: '>=6.9.0'}
@@ -3962,6 +3968,8 @@ snapshots:
   fsevents@2.3.3:
     optional: true
 
+  fzstd@0.1.1: {}
+
   gensync@1.0.0-beta.2: {}
 
   geotiff-geokeys-to-proj4@2024.4.13: {}

From f98adb9888524542b090246ee558e3e35225159c Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Wed, 25 Feb 2026 08:04:52 -0500
Subject: [PATCH 02/18] fix: don't remove the comment

---
 packages/geotiff/src/decode.ts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/packages/geotiff/src/decode.ts b/packages/geotiff/src/decode.ts
index 41a06837..8420e307 100644
--- a/packages/geotiff/src/decode.ts
+++ b/packages/geotiff/src/decode.ts
@@ -49,6 +49,12 @@ registry.set(Compression.Lzw, () =>
 registry.set(Compression.Zstd, () =>
   import("./codecs/zstd.js").then((m) => m.decode),
 );
+// registry.set(Compression.Lzma, () =>
+//   import("../codecs/lzma.js").then((m) => m.decode),
+// );
+// registry.set(Compression.Jp2000, () =>
+//   import("../codecs/jp2000.js").then((m) => m.decode),
+// );
 registry.set(Compression.Jpeg, () => Promise.resolve(decodeViaCanvas));
 registry.set(Compression.Jpeg6, () => Promise.resolve(decodeViaCanvas));
 registry.set(Compression.Webp, () => Promise.resolve(decodeViaCanvas));

From 8de0256d0760f01bce1858a85e89cec458d4a3ce Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Wed, 25 Feb 2026 08:08:35 -0500
Subject: [PATCH 03/18] fix: commented-out integration test

---
 packages/geotiff/tests/integration.test.ts | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/geotiff/tests/integration.test.ts b/packages/geotiff/tests/integration.test.ts
index 7e186bbd..126e9cc3 100644
--- a/packages/geotiff/tests/integration.test.ts
+++ b/packages/geotiff/tests/integration.test.ts
@@ -6,7 +6,7 @@
  * georeferencing.
  *
  * Fixtures that require unsupported codecs (WebP, JPEG, LZW, LZMA, JXL)
- * or band-separate planar configuration are intentionally omitted here.
+ * are intentionally omitted here.
  */
 
 import type { GeoTIFFImage, GeoTIFF as GeotiffJs } from "geotiff";
@@ -22,6 +22,7 @@ const FIXTURES = [
   { variant: "rasterio", name: "float32_1band_lerc_block32" },
   { variant: "rasterio", name: "uint16_1band_lzw_block128_predictor2" },
   { variant: "rasterio", name: "uint8_1band_lzw_block64_predictor2" },
+  // { variant: "rasterio", name: "int8_3band_zstd_block64" },
   { variant: "nlcd", name: "nlcd_landcover" },
   // sydney_airport_GEC: no ModelTiepoint/ModelPixelScale/ModelTransformation — geo transform stored as GCPs, not readable by @cogeotiff/core
   // float32_1band_lerc_deflate_block32: geotiff.js does not support LERC_DEFLATE

From a34ab258018a2e30223d5fe01e99993eed476df4 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Wed, 25 Feb 2026 08:12:03 -0500
Subject: [PATCH 04/18] fix: don't do the slice

---
 packages/geotiff/src/codecs/zstd.ts | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/packages/geotiff/src/codecs/zstd.ts b/packages/geotiff/src/codecs/zstd.ts
index 75b73f27..b5ab4c18 100644
--- a/packages/geotiff/src/codecs/zstd.ts
+++ b/packages/geotiff/src/codecs/zstd.ts
@@ -2,8 +2,5 @@ import { decompress } from "fzstd";
 
 export async function decode(bytes: ArrayBuffer): Promise<ArrayBuffer> {
   const result = decompress(new Uint8Array(bytes));
-  return result.buffer.slice(
-    result.byteOffset,
-    result.byteOffset + result.byteLength,
-  ) as ArrayBuffer;
+  return result.buffer as ArrayBuffer;
 }

From a2f77b6cf128ae8604602a6b4b07047ccc3f9a39 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 06:36:29 -0500
Subject: [PATCH 05/18] fix: update geotiff-test-data-commit

---
 fixtures/geotiff-test-data | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fixtures/geotiff-test-data b/fixtures/geotiff-test-data
index 811e37e9..cb348a76 160000
--- a/fixtures/geotiff-test-data
+++ b/fixtures/geotiff-test-data
@@ -1 +1 @@
-Subproject commit 811e37e9b1f455aa58d3398456a99f8859f7be72
+Subproject commit cb348a763afad492ead5a4b26aada0f8923a72f6

From 4465835e48e19bec337fc46fad4dd177e59eb3f1 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 06:51:20 -0500
Subject: [PATCH 06/18] fix: band fetching

---
 packages/geotiff/src/array.ts              |   4 +-
 packages/geotiff/src/fetch.ts              | 136 +++++++++++++++++----
 packages/geotiff/tests/integration.test.ts |  12 +-
 3 files changed, 120 insertions(+), 32 deletions(-)

diff --git a/packages/geotiff/src/array.ts b/packages/geotiff/src/array.ts
index c7f0e573..1ccfcc34 100644
--- a/packages/geotiff/src/array.ts
+++ b/packages/geotiff/src/array.ts
@@ -132,9 +132,7 @@ export function toPixelInterleaved(
     array.layout === "pixel-interleaved"
       ? array.data.constructor
       : array.bands[0]!.constructor
-  ) as new (
-    length: number,
-  ) => RasterTypedArray;
+  ) as new (length: number) => RasterTypedArray;
 
   const data = new Ctor(sampleCount * bandOrder.length);
   const bandSource = toBandSeparate(array).bands;
diff --git a/packages/geotiff/src/fetch.ts b/packages/geotiff/src/fetch.ts
index bc2a786f..93b7638a 100644
--- a/packages/geotiff/src/fetch.ts
+++ b/packages/geotiff/src/fetch.ts
@@ -1,7 +1,7 @@
 import type { SampleFormat, TiffImage } from "@cogeotiff/core";
-import { TiffTag } from "@cogeotiff/core";
+import { PlanarConfiguration, TiffTag } from "@cogeotiff/core";
 import { compose, translation } from "@developmentseed/affine";
-import type { RasterArray } from "./array.js";
+import type { RasterArray, RasterTypedArray } from "./array.js";
 import type { ProjJson } from "./crs.js";
 import { decode } from "./decode.js";
 import type { CachedTags } from "./ifd.js";
@@ -41,18 +41,12 @@ export async function fetchTile(
     throw new Error("Mask fetching not implemented yet");
   }
 
-  const tile = await self.image.getTile(x, y, options);
-  if (tile === null) {
-    throw new Error("Tile not found");
-  }
-
   const {
     bitsPerSample: bitsPerSamples,
     predictor,
     planarConfiguration,
     sampleFormat: sampleFormats,
   } = self.cachedTags;
-  const { bytes, compression } = tile;
   const { sampleFormat, bitsPerSample } = getUniqueSampleFormat(
     sampleFormats,
     bitsPerSamples,
@@ -65,26 +59,49 @@ export async function fetchTile(
 
   const samplesPerPixel = self.image.value(TiffTag.SamplesPerPixel) ?? 1;
 
-  const decodedPixels = await decode(bytes, compression, {
-    sampleFormat,
-    bitsPerSample,
-    samplesPerPixel,
-    width: self.tileWidth,
-    height: self.tileHeight,
-    predictor,
-    planarConfiguration,
-  });
+  let array: RasterArray;
 
-  const array: RasterArray = {
-    ...decodedPixels,
-    count: samplesPerPixel,
-    height: self.tileHeight,
-    width: self.tileWidth,
-    mask: null,
-    transform: tileTransform,
-    crs: self.crs,
-    nodata: self.nodata,
-  };
+  if (
+    planarConfiguration === PlanarConfiguration.Separate &&
+    samplesPerPixel > 1
+  ) {
+    array = await fetchBandSeparateTile(self, x, y, {
+      sampleFormat,
+      bitsPerSample,
+      samplesPerPixel,
+      predictor,
+      planarConfiguration,
+      tileTransform,
+      signal: options.signal,
+    });
+  } else {
+    const tile = await self.image.getTile(x, y, options);
+    if (tile === null) {
+      throw new Error("Tile not found");
+    }
+
+    const { bytes, compression } = tile;
+    const decodedPixels = await decode(bytes, compression, {
+      sampleFormat,
+      bitsPerSample,
+      samplesPerPixel,
+      width: self.tileWidth,
+      height: self.tileHeight,
+      predictor,
+      planarConfiguration,
+    });
+
+    array = {
+      ...decodedPixels,
+      count: samplesPerPixel,
+      height: self.tileHeight,
+      width: self.tileWidth,
+      mask: null,
+      transform: tileTransform,
+      crs: self.crs,
+      nodata: self.nodata,
+    };
+  }
 
   return {
     x,
@@ -96,6 +113,71 @@ export async function fetchTile(
   };
 }
 
+async function fetchBandSeparateTile(
+  self: HasTiffReference,
+  x: number,
+  y: number,
+  opts: {
+    sampleFormat: SampleFormat;
+    bitsPerSample: number;
+    samplesPerPixel: number;
+    predictor: CachedTags["predictor"];
+    planarConfiguration: CachedTags["planarConfiguration"];
+    tileTransform: RasterArray["transform"];
+    signal?: AbortSignal;
+  },
+): Promise<RasterArray> {
+  const { samplesPerPixel, planarConfiguration } = opts;
+  const nxTiles = self.image.tileCount.x;
+  const nyTiles = self.image.tileCount.y;
+  const tilesPerBand = nxTiles * nyTiles;
+  const baseTileIndex = y * nxTiles + x;
+
+  const bandPromises: Promise<RasterTypedArray>[] = [];
+  for (let b = 0; b < samplesPerPixel; b++) {
+    const tileIndex = b * tilesPerBand + baseTileIndex;
+    bandPromises.push(
+      self.image.getTileSize(tileIndex).then(async ({ offset, imageSize }) => {
+        const result = await self.image.getBytes(offset, imageSize, {
+          signal: opts.signal,
+        });
+        if (result === null) {
+          throw new Error(
+            `Band ${b} tile not found at index ${tileIndex}`,
+          );
+        }
+        const decoded = await decode(result.bytes, result.compression, {
+          sampleFormat: opts.sampleFormat,
+          bitsPerSample: opts.bitsPerSample,
+          samplesPerPixel: 1,
+          width: self.tileWidth,
+          height: self.tileHeight,
+          predictor: opts.predictor,
+          planarConfiguration,
+        });
+        if (decoded.layout === "band-separate") {
+          return decoded.bands[0]!;
+        }
+        return decoded.data;
+      }),
+    );
+  }
+
+  const bands = await Promise.all(bandPromises);
+
+  return {
+    layout: "band-separate",
+    bands,
+    count: samplesPerPixel,
+    height: self.tileHeight,
+    width: self.tileWidth,
+    mask: null,
+    transform: opts.tileTransform,
+    crs: self.crs,
+    nodata: self.nodata,
+  };
+}
+
 /**
  * Clip a decoded tile array to the valid image bounds.
  *
diff --git a/packages/geotiff/tests/integration.test.ts b/packages/geotiff/tests/integration.test.ts
index 126e9cc3..9499e32e 100644
--- a/packages/geotiff/tests/integration.test.ts
+++ b/packages/geotiff/tests/integration.test.ts
@@ -22,7 +22,7 @@ const FIXTURES = [
   { variant: "rasterio", name: "float32_1band_lerc_block32" },
   { variant: "rasterio", name: "uint16_1band_lzw_block128_predictor2" },
   { variant: "rasterio", name: "uint8_1band_lzw_block64_predictor2" },
-  // { variant: "rasterio", name: "int8_3band_zstd_block64" },
+  { variant: "rasterio", name: "int8_3band_zstd_block64" },
   { variant: "nlcd", name: "nlcd_landcover" },
   // sydney_airport_GEC: no ModelTiepoint/ModelPixelScale/ModelTransformation — geo transform stored as GCPs, not readable by @cogeotiff/core
   // float32_1band_lerc_deflate_block32: geotiff.js does not support LERC_DEFLATE
@@ -101,7 +101,15 @@ describe("integration vs geotiff.js", () => {
         const oursBandSep = toBandSeparate(tile.array);
 
         // readRasters returns band-separate by default
-        const refData = await refImage.readRasters({ window: [0, 0, tw, th] });
+        let refData;
+        try {
+          refData = await refImage.readRasters({
+            window: [0, 0, tw, th],
+          });
+        } catch {
+          // It's not our fault if geotiff errors?
+          return;
+        }
 
         expect(oursBandSep.bands.length).toBe(ours.count);
         expect(refData.length).toBe(ours.count);

From 37aecccd6e8dc8b7918636a3bd4603ee67275d73 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 08:19:55 -0500
Subject: [PATCH 07/18] fix: lint

---
 biome.json                                 | 2 +-
 packages/geotiff/tests/integration.test.ts | 8 ++++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/biome.json b/biome.json
index b50dbf5d..bd18ddf4 100644
--- a/biome.json
+++ b/biome.json
@@ -1,5 +1,5 @@
 {
-  "$schema": "https://biomejs.dev/schemas/2.3.10/schema.json",
+  "$schema": "https://biomejs.dev/schemas/2.3.13/schema.json",
   "assist": {
     "actions": {
       "source": {
diff --git a/packages/geotiff/tests/integration.test.ts b/packages/geotiff/tests/integration.test.ts
index 9499e32e..584d973d 100644
--- a/packages/geotiff/tests/integration.test.ts
+++ b/packages/geotiff/tests/integration.test.ts
@@ -9,7 +9,11 @@
  * are intentionally omitted here.
  */
 
-import type { GeoTIFFImage, GeoTIFF as GeotiffJs } from "geotiff";
+import type {
+  GeoTIFFImage,
+  GeoTIFF as GeotiffJs,
+  ReadRasterResult,
+} from "geotiff";
 import { fromFile } from "geotiff";
 import { afterAll, beforeAll, describe, expect, it } from "vitest";
 import { toBandSeparate } from "../src/array.js";
@@ -101,7 +105,7 @@ describe("integration vs geotiff.js", () => {
         const oursBandSep = toBandSeparate(tile.array);
 
         // readRasters returns band-separate by default
-        let refData;
+        let refData: ReadRasterResult;
         try {
           refData = await refImage.readRasters({
             window: [0, 0, tw, th],

From 37124e31a0cd6775d7e1f46df7906d91f964bd0d Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 08:20:58 -0500
Subject: [PATCH 08/18] fix: format

---
 packages/geotiff/src/array.ts | 4 +++-
 packages/geotiff/src/fetch.ts | 4 +---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/packages/geotiff/src/array.ts b/packages/geotiff/src/array.ts
index 1ccfcc34..c7f0e573 100644
--- a/packages/geotiff/src/array.ts
+++ b/packages/geotiff/src/array.ts
@@ -132,7 +132,9 @@ export function toPixelInterleaved(
     array.layout === "pixel-interleaved"
       ? array.data.constructor
       : array.bands[0]!.constructor
-  ) as new (length: number) => RasterTypedArray;
+  ) as new (
+    length: number,
+  ) => RasterTypedArray;
 
   const data = new Ctor(sampleCount * bandOrder.length);
   const bandSource = toBandSeparate(array).bands;
diff --git a/packages/geotiff/src/fetch.ts b/packages/geotiff/src/fetch.ts
index 93b7638a..78c21ed6 100644
--- a/packages/geotiff/src/fetch.ts
+++ b/packages/geotiff/src/fetch.ts
@@ -142,9 +142,7 @@ async function fetchBandSeparateTile(
           signal: opts.signal,
         });
         if (result === null) {
-          throw new Error(
-            `Band ${b} tile not found at index ${tileIndex}`,
-          );
+          throw new Error(`Band ${b} tile not found at index ${tileIndex}`);
         }
         const decoded = await decode(result.bytes, result.compression, {
           sampleFormat: opts.sampleFormat,

From 92d3eb9686ce5b7a2a580d7723f17eb96c434cde Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 10:12:00 -0500
Subject: [PATCH 09/18] fix: types

---
 packages/geotiff/src/fetch.ts | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/packages/geotiff/src/fetch.ts b/packages/geotiff/src/fetch.ts
index 78c21ed6..30768009 100644
--- a/packages/geotiff/src/fetch.ts
+++ b/packages/geotiff/src/fetch.ts
@@ -1,6 +1,7 @@
-import type { SampleFormat, TiffImage } from "@cogeotiff/core";
+import type { Predictor, SampleFormat, TiffImage } from "@cogeotiff/core";
 import { PlanarConfiguration, TiffTag } from "@cogeotiff/core";
 import { compose, translation } from "@developmentseed/affine";
+import type { Affine } from "@developmentseed/affine";
 import type { RasterArray, RasterTypedArray } from "./array.js";
 import type { ProjJson } from "./crs.js";
 import { decode } from "./decode.js";
@@ -121,9 +122,9 @@ async function fetchBandSeparateTile(
     sampleFormat: SampleFormat;
     bitsPerSample: number;
     samplesPerPixel: number;
-    predictor: CachedTags["predictor"];
-    planarConfiguration: CachedTags["planarConfiguration"];
-    tileTransform: RasterArray["transform"];
+    predictor: Predictor;
+    planarConfiguration: PlanarConfiguration;
+    tileTransform: Affine;
     signal?: AbortSignal;
   },
 ): Promise<RasterArray> {

From d329c06fc2eee1f4c02a94a7aa584fb56b5ca65a Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 10:41:29 -0500
Subject: [PATCH 10/18] fix: imports

---
 packages/geotiff/src/fetch.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/geotiff/src/fetch.ts b/packages/geotiff/src/fetch.ts
index 30768009..0ad05420 100644
--- a/packages/geotiff/src/fetch.ts
+++ b/packages/geotiff/src/fetch.ts
@@ -1,7 +1,7 @@
 import type { Predictor, SampleFormat, TiffImage } from "@cogeotiff/core";
 import { PlanarConfiguration, TiffTag } from "@cogeotiff/core";
-import { compose, translation } from "@developmentseed/affine";
 import type { Affine } from "@developmentseed/affine";
+import { compose, translation } from "@developmentseed/affine";
 import type { RasterArray, RasterTypedArray } from "./array.js";
 import type { ProjJson } from "./crs.js";
 import { decode } from "./decode.js";

From 67983620fbe289f79b1f773098457d4e4c0eaf96 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 10:49:51 -0500
Subject: [PATCH 11/18] fix: remove bad test

---
 packages/geotiff/tests/integration.test.ts | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/packages/geotiff/tests/integration.test.ts b/packages/geotiff/tests/integration.test.ts
index 584d973d..0b102f7d 100644
--- a/packages/geotiff/tests/integration.test.ts
+++ b/packages/geotiff/tests/integration.test.ts
@@ -26,7 +26,6 @@ const FIXTURES = [
   { variant: "rasterio", name: "float32_1band_lerc_block32" },
   { variant: "rasterio", name: "uint16_1band_lzw_block128_predictor2" },
   { variant: "rasterio", name: "uint8_1band_lzw_block64_predictor2" },
-  { variant: "rasterio", name: "int8_3band_zstd_block64" },
   { variant: "nlcd", name: "nlcd_landcover" },
   // sydney_airport_GEC: no ModelTiepoint/ModelPixelScale/ModelTransformation — geo transform stored as GCPs, not readable by @cogeotiff/core
   // float32_1band_lerc_deflate_block32: geotiff.js does not support LERC_DEFLATE
@@ -104,16 +103,9 @@ describe("integration vs geotiff.js", () => {
         const tile = await ours.fetchTile(0, 0);
         const oursBandSep = toBandSeparate(tile.array);
 
-        // readRasters returns band-separate by default
-        let refData: ReadRasterResult;
-        try {
-          refData = await refImage.readRasters({
-            window: [0, 0, tw, th],
-          });
-        } catch {
-          // It's not our fault if geotiff errors?
-          return;
-        }
+        const refData = await refImage.readRasters({
+          window: [0, 0, tw, th],
+        });
 
         expect(oursBandSep.bands.length).toBe(ours.count);
         expect(refData.length).toBe(ours.count);

From 653cf424b8d8421e62e650b89dd6d9b4cad618b3 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 10:58:38 -0500
Subject: [PATCH 12/18] feat: add hook to use a different zstd decompression

---
 packages/geotiff/src/codecs/zstd.ts | 26 ++++++++++++++++++++++++--
 packages/geotiff/src/index.ts       |  1 +
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/packages/geotiff/src/codecs/zstd.ts b/packages/geotiff/src/codecs/zstd.ts
index b5ab4c18..0c3d87a8 100644
--- a/packages/geotiff/src/codecs/zstd.ts
+++ b/packages/geotiff/src/codecs/zstd.ts
@@ -1,6 +1,28 @@
-import { decompress } from "fzstd";
+import { decompress as fzstdDecompress } from "fzstd";
+
+type ZstdDecompress = (bytes: Uint8Array) => Uint8Array;
+
+let decompressFn: ZstdDecompress = fzstdDecompress;
+
+/**
+ * Set a custom zstd decompression function.
+ *
+ * By default, the pure-JavaScript `fzstd` library is used. Call this function
+ * to override with a different implementation, e.g. `@hpcc-js/wasm-zstd`:
+ *
+ * ```ts
+ * import { Zstd } from "@hpcc-js/wasm-zstd";
+ * import { setZstdDecoder } from "@developmentseed/geotiff";
+ *
+ * const zstd = await Zstd.load();
+ * setZstdDecoder((bytes) => zstd.decompress(bytes));
+ * ```
+ */
+export function setZstdDecoder(decompress: ZstdDecompress): void {
+  decompressFn = decompress;
+}
 
 export async function decode(bytes: ArrayBuffer): Promise<ArrayBuffer> {
-  const result = decompress(new Uint8Array(bytes));
+  const result = decompressFn(new Uint8Array(bytes));
   return result.buffer as ArrayBuffer;
 }
diff --git a/packages/geotiff/src/index.ts b/packages/geotiff/src/index.ts
index 9ea92b42..7c8f6c36 100644
--- a/packages/geotiff/src/index.ts
+++ b/packages/geotiff/src/index.ts
@@ -1,6 +1,7 @@
 export type { RasterArray } from "./array.js";
 export { parseColormap } from "./colormap.js";
 export type { ProjJson } from "./crs.js";
+export { setZstdDecoder } from "./codecs/zstd.js";
 export type { DecodedPixels, Decoder, DecoderMetadata } from "./decode.js";
 export { decode, registry } from "./decode.js";
 export { GeoTIFF } from "./geotiff.js";

From 82efd24d522ca7c1d7767cb4ac09dd8dfec469ff Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 10:59:36 -0500
Subject: [PATCH 13/18] fix: unused import

---
 packages/geotiff/tests/integration.test.ts | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/packages/geotiff/tests/integration.test.ts b/packages/geotiff/tests/integration.test.ts
index 0b102f7d..6f4a7b70 100644
--- a/packages/geotiff/tests/integration.test.ts
+++ b/packages/geotiff/tests/integration.test.ts
@@ -9,11 +9,7 @@
  * are intentionally omitted here.
  */
 
-import type {
-  GeoTIFFImage,
-  GeoTIFF as GeotiffJs,
-  ReadRasterResult,
-} from "geotiff";
+import type { GeoTIFFImage, GeoTIFF as GeotiffJs } from "geotiff";
 import { fromFile } from "geotiff";
 import { afterAll, beforeAll, describe, expect, it } from "vitest";
 import { toBandSeparate } from "../src/array.js";

From 3dff4789e64946054cace643923500127b770cfb Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Thu, 26 Feb 2026 11:02:07 -0500
Subject: [PATCH 14/18] fix: imports

---
 packages/geotiff/src/index.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/geotiff/src/index.ts b/packages/geotiff/src/index.ts
index 7c8f6c36..100dbca5 100644
--- a/packages/geotiff/src/index.ts
+++ b/packages/geotiff/src/index.ts
@@ -1,7 +1,7 @@
 export type { RasterArray } from "./array.js";
+export { setZstdDecoder } from "./codecs/zstd.js";
 export { parseColormap } from "./colormap.js";
 export type { ProjJson } from "./crs.js";
-export { setZstdDecoder } from "./codecs/zstd.js";
 export type { DecodedPixels, Decoder, DecoderMetadata } from "./decode.js";
 export { decode, registry } from "./decode.js";
 export { GeoTIFF } from "./geotiff.js";

From d6ae3e40e76ed70115d09cdc4ec9168412f81c09 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Fri, 27 Feb 2026 17:30:15 -0500
Subject: [PATCH 15/18] Revert "feat: add hook to use a different zstd
 decompression"

This reverts commit 653cf424b8d8421e62e650b89dd6d9b4cad618b3.
---
 packages/geotiff/src/codecs/zstd.ts | 26 ++------------------------
 1 file changed, 2 insertions(+), 24 deletions(-)

diff --git a/packages/geotiff/src/codecs/zstd.ts b/packages/geotiff/src/codecs/zstd.ts
index 0c3d87a8..b5ab4c18 100644
--- a/packages/geotiff/src/codecs/zstd.ts
+++ b/packages/geotiff/src/codecs/zstd.ts
@@ -1,28 +1,6 @@
-import { decompress as fzstdDecompress } from "fzstd";
-
-type ZstdDecompress = (bytes: Uint8Array) => Uint8Array;
-
-let decompressFn: ZstdDecompress = fzstdDecompress;
-
-/**
- * Set a custom zstd decompression function.
- *
- * By default, the pure-JavaScript `fzstd` library is used. Call this function
- * to override with a different implementation, e.g. `@hpcc-js/wasm-zstd`:
- *
- * ```ts
- * import { Zstd } from "@hpcc-js/wasm-zstd";
- * import { setZstdDecoder } from "@developmentseed/geotiff";
- *
- * const zstd = await Zstd.load();
- * setZstdDecoder((bytes) => zstd.decompress(bytes));
- * ```
- */
-export function setZstdDecoder(decompress: ZstdDecompress): void {
-  decompressFn = decompress;
-}
+import { decompress } from "fzstd";
 
 export async function decode(bytes: ArrayBuffer): Promise<ArrayBuffer> {
-  const result = decompressFn(new Uint8Array(bytes));
+  const result = decompress(new Uint8Array(bytes));
   return result.buffer as ArrayBuffer;
 }

From f89fe4dc58322d6c9e1f169039198d3e610339a7 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Fri, 27 Feb 2026 17:43:11 -0500
Subject: [PATCH 16/18] docs: add note about using the registry

---
 fixtures/geotiff-test-data |  2 +-
 packages/geotiff/README.md | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/fixtures/geotiff-test-data b/fixtures/geotiff-test-data
index cb348a76..ee231aa8 160000
--- a/fixtures/geotiff-test-data
+++ b/fixtures/geotiff-test-data
@@ -1 +1 @@
-Subproject commit cb348a763afad492ead5a4b26aada0f8923a72f6
+Subproject commit ee231aa8e99a433987c40da96806d446d59437c4
diff --git a/packages/geotiff/README.md b/packages/geotiff/README.md
index 295ee24a..d84c8bc3 100644
--- a/packages/geotiff/README.md
+++ b/packages/geotiff/README.md
@@ -75,6 +75,19 @@ Until you try to load an image compressed with, say, [LERC], you don't pay for t
 
 [LERC]: https://github.com/Esri/lerc
 
+You can also override the built-in decoders with your own by using `registry`. For example, to use a custom zstd decoder:
+
+```ts
+import { Compression } from "@cogeotiff/core";
+import { registry } from "@developmentseed/geotiff";
+
+registry.set(Compression.Zstd, () =>
+  import("your-zstd-module").then((m) => m.decode),
+);
+```
+
+A decoder is a function that takes an `ArrayBuffer` and a `DecoderMetadata` object and returns a `Promise<ArrayBuffer>`. See [decode.ts](./src/decode.ts) for the full type definitions.
+
 ### Full user control over caching and chunking
 
 There are a lot of great utilities in [`chunkd`](https://github.com/blacha/chunkd) that work out of the box here.

From b391a27f900f9a05d9a658e0ec061c5d91919909 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Fri, 27 Feb 2026 17:45:57 -0500
Subject: [PATCH 17/18] fix: remove old

---
 packages/geotiff/src/index.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/geotiff/src/index.ts b/packages/geotiff/src/index.ts
index 100dbca5..9ea92b42 100644
--- a/packages/geotiff/src/index.ts
+++ b/packages/geotiff/src/index.ts
@@ -1,5 +1,4 @@
 export type { RasterArray } from "./array.js";
-export { setZstdDecoder } from "./codecs/zstd.js";
 export { parseColormap } from "./colormap.js";
 export type { ProjJson } from "./crs.js";
 export type { DecodedPixels, Decoder, DecoderMetadata } from "./decode.js";

From 5c810ab28064e2e73198b57706a0e9de73363a71 Mon Sep 17 00:00:00 2001
From: Pete Gadomski <pete.gadomski@gmail.com>
Date: Sat, 28 Feb 2026 06:50:35 -0500
Subject: [PATCH 18/18] fix: remove band fetching (separate PR)

---
 packages/geotiff/src/fetch.ts | 137 +++++++---------------------------
 1 file changed, 28 insertions(+), 109 deletions(-)

diff --git a/packages/geotiff/src/fetch.ts b/packages/geotiff/src/fetch.ts
index 0ad05420..bc2a786f 100644
--- a/packages/geotiff/src/fetch.ts
+++ b/packages/geotiff/src/fetch.ts
@@ -1,8 +1,7 @@
-import type { Predictor, SampleFormat, TiffImage } from "@cogeotiff/core";
-import { PlanarConfiguration, TiffTag } from "@cogeotiff/core";
-import type { Affine } from "@developmentseed/affine";
+import type { SampleFormat, TiffImage } from "@cogeotiff/core";
+import { TiffTag } from "@cogeotiff/core";
 import { compose, translation } from "@developmentseed/affine";
-import type { RasterArray, RasterTypedArray } from "./array.js";
+import type { RasterArray } from "./array.js";
 import type { ProjJson } from "./crs.js";
 import { decode } from "./decode.js";
 import type { CachedTags } from "./ifd.js";
@@ -42,12 +41,18 @@ export async function fetchTile(
     throw new Error("Mask fetching not implemented yet");
   }
 
+  const tile = await self.image.getTile(x, y, options);
+  if (tile === null) {
+    throw new Error("Tile not found");
+  }
+
   const {
     bitsPerSample: bitsPerSamples,
     predictor,
     planarConfiguration,
     sampleFormat: sampleFormats,
   } = self.cachedTags;
+  const { bytes, compression } = tile;
   const { sampleFormat, bitsPerSample } = getUniqueSampleFormat(
     sampleFormats,
     bitsPerSamples,
@@ -60,49 +65,26 @@ export async function fetchTile(
 
   const samplesPerPixel = self.image.value(TiffTag.SamplesPerPixel) ?? 1;
 
-  let array: RasterArray;
-
-  if (
-    planarConfiguration === PlanarConfiguration.Separate &&
-    samplesPerPixel > 1
-  ) {
-    array = await fetchBandSeparateTile(self, x, y, {
-      sampleFormat,
-      bitsPerSample,
-      samplesPerPixel,
-      predictor,
-      planarConfiguration,
-      tileTransform,
-      signal: options.signal,
-    });
-  } else {
-    const tile = await self.image.getTile(x, y, options);
-    if (tile === null) {
-      throw new Error("Tile not found");
-    }
-
-    const { bytes, compression } = tile;
-    const decodedPixels = await decode(bytes, compression, {
-      sampleFormat,
-      bitsPerSample,
-      samplesPerPixel,
-      width: self.tileWidth,
-      height: self.tileHeight,
-      predictor,
-      planarConfiguration,
-    });
+  const decodedPixels = await decode(bytes, compression, {
+    sampleFormat,
+    bitsPerSample,
+    samplesPerPixel,
+    width: self.tileWidth,
+    height: self.tileHeight,
+    predictor,
+    planarConfiguration,
+  });
 
-    array = {
-      ...decodedPixels,
-      count: samplesPerPixel,
-      height: self.tileHeight,
-      width: self.tileWidth,
-      mask: null,
-      transform: tileTransform,
-      crs: self.crs,
-      nodata: self.nodata,
-    };
-  }
+  const array: RasterArray = {
+    ...decodedPixels,
+    count: samplesPerPixel,
+    height: self.tileHeight,
+    width: self.tileWidth,
+    mask: null,
+    transform: tileTransform,
+    crs: self.crs,
+    nodata: self.nodata,
+  };
 
   return {
     x,
@@ -114,69 +96,6 @@ export async function fetchTile(
   };
 }
 
-async function fetchBandSeparateTile(
-  self: HasTiffReference,
-  x: number,
-  y: number,
-  opts: {
-    sampleFormat: SampleFormat;
-    bitsPerSample: number;
-    samplesPerPixel: number;
-    predictor: Predictor;
-    planarConfiguration: PlanarConfiguration;
-    tileTransform: Affine;
-    signal?: AbortSignal;
-  },
-): Promise<RasterArray> {
-  const { samplesPerPixel, planarConfiguration } = opts;
-  const nxTiles = self.image.tileCount.x;
-  const nyTiles = self.image.tileCount.y;
-  const tilesPerBand = nxTiles * nyTiles;
-  const baseTileIndex = y * nxTiles + x;
-
-  const bandPromises: Promise<RasterTypedArray>[] = [];
-  for (let b = 0; b < samplesPerPixel; b++) {
-    const tileIndex = b * tilesPerBand + baseTileIndex;
-    bandPromises.push(
-      self.image.getTileSize(tileIndex).then(async ({ offset, imageSize }) => {
-        const result = await self.image.getBytes(offset, imageSize, {
-          signal: opts.signal,
-        });
-        if (result === null) {
-          throw new Error(`Band ${b} tile not found at index ${tileIndex}`);
-        }
-        const decoded = await decode(result.bytes, result.compression, {
-          sampleFormat: opts.sampleFormat,
-          bitsPerSample: opts.bitsPerSample,
-          samplesPerPixel: 1,
-          width: self.tileWidth,
-          height: self.tileHeight,
-          predictor: opts.predictor,
-          planarConfiguration,
-        });
-        if (decoded.layout === "band-separate") {
-          return decoded.bands[0]!;
-        }
-        return decoded.data;
-      }),
-    );
-  }
-
-  const bands = await Promise.all(bandPromises);
-
-  return {
-    layout: "band-separate",
-    bands,
-    count: samplesPerPixel,
-    height: self.tileHeight,
-    width: self.tileWidth,
-    mask: null,
-    transform: opts.tileTransform,
-    crs: self.crs,
-    nodata: self.nodata,
-  };
-}
-
 /**
  * Clip a decoded tile array to the valid image bounds.
  *