matmen · Oct 16, 2026 · Oct 16, 2026
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -35,13 +35,23 @@
   character, and decomposes characters the fonts lack where one has their parts, like HarfBuzz.
 - Fallback fonts are only loaded when the text needs them, and glyphs (also decoded and scaled emoji bitmaps) are
   kept per font and size across calls.
+- `DecodeOptions.maxPixels` and `AnimationDecodeOptions.maxPixels` (default 268,402,689, that's 16383², like sharp):
+  larger images, and animations whose frames take more pixels together, throw a RangeError before anything that size
+  is allocated. Tiny files declaring huge images (decompression bombs) could take gigabytes or kill the process: a
+  250-byte JPEG of 65500x65500, a 115 kB GIF with 5000 frames on a 4000x4000 screen. `maxPixels: Infinity` lifts the
+  limit. TIFFs also can't take more than 8 bytes of samples per pixel of the limit, or tiles much larger than the
+  image.
 
 ### Performance
 
 - Lossless WebP encoding is about 40% faster and decoding about 15% faster (1920×1080 photo: 735 instead of 1220 ms,
   82 instead of 95 ms), with identical output: the predictors run as one loop per mode instead of a switch per pixel,
   residual costs come from a table, and the LZ77 search hashes every pixel pair once.
 
+- Decoding PNGs takes less memory (an 8000x8000 RGBA image: 785 instead of 1272 MB at most): the rows are unfiltered in
+  place, and `Image.decode` keeps the decoded pixels instead of copying them. `Animation.decode` decodes still PNGs like
+  images (10 times as fast for large ones), and composites APNG frames that replace pixels row by row.
+
 ### Fixes
 
 - The outline of `Image.renderText` (`strokeWidth`) showed through translucent text, it now only shows around the
@@ -56,6 +66,11 @@
   of a RangeError, and text larger than 2^28 pixels throws.
 - Glyph outlines reaching far outside their bitmap rasterize correctly (the parts outside used to change the slope of
   the edges inside).
+- Damaged images throw "Image: damaged or truncated image data" (with the original RangeError as its cause) instead
+  of RangeErrors from reading past their end. JPEGs with more than 4 components are rejected (each took memory the size
+  of the image).
+- `blur` and `sharpen` hung with an infinite radius, they throw a RangeError now; huge finite radii take as long as
+  small ones (`blur(1e9)` took minutes).
 
 ## 3.2.1
 

diff --git a/README.md b/README.md
@@ -28,6 +28,8 @@ deno add jsr:@matmen/imagescript     # Deno (npm:imagescript works too)
   - WebPs (lossy, lossless and with alpha; bit-exact with libwebp)
   - TGAs (color mapped, truecolor and greyscale; uncompressed and run length encoded)
   - JPEGs, TIFFs, PNGs and WebPs are rotated as their Exif (or, for PNGs, XMP) orientation says
+  - images larger than 268 megapixels (`maxPixels`) are rejected before decoding, so small files declaring huge images
+    can't exhaust the memory
 - [Decoding animations](https://imagescript.matmen.dev/classes/Animation.html#decode) (GIF, APNG and WebP) with all
   frames, durations and disposal modes
 - [Rendering SVGs](https://imagescript.matmen.dev/classes/Image.html#rendersvg) (shapes, paths, gradients, strokes, clip paths,

diff --git a/src/animation.ts b/src/animation.ts
@@ -8,13 +8,14 @@ import { ImageType } from './image-type.ts';
 import { optimize, OptimizeOptions, OptimizedFrame } from './util/optimize.ts';
 import { Metadata, resolveMetadata, pngText, exifData, gifComments } from './metadata.ts';
 import { isOptions } from './util/options.ts';
+import { MAX_PIXELS, decoding } from './util/limits.ts';
 
 // loop counts: ImageScript (like GIF) counts repetitions (-1 forever, 0 play once), APNG and WebP count plays (0 forever)
 const toPlays = (loopCount: number): number => loopCount < 0 ? 0 : loopCount + 1;
 const fromPlays = (plays: number): number => plays === 0 ? -1 : plays - 1;
 
 // frames decoded fully composited, as full canvas frames
-function canvasFrames(width: number, height: number, frames: Array<{ pixels: Uint8Array, duration: number }>): Frame[] {
+function canvasFrames(width: number, height: number, frames: Array<{ pixels: Uint8Array | Uint8ClampedArray, duration: number }>): Frame[] {
     return frames.map(({ pixels, duration }) => {
         const frame = new Frame(width, height, duration, 0, 0, Frame.DISPOSAL_BACKGROUND);
         // the composited frames are copies already, the frame can keep them
@@ -33,6 +34,12 @@ export interface AnimationOptions {
 export interface AnimationDecodeOptions {
     /** Whether to stop decoding after the first frame. Default: `false` */
     onlyFirstFrame?: boolean;
+    /**
+     * The most pixels to decode, of all frames together (every frame is a full canvas): larger animations throw a
+     * RangeError before anything that size is allocated, so small files declaring huge animations (decompression
+     * bombs) can't exhaust the memory. Default: `268402689` (16383², like sharp), `Infinity` for no limit
+     */
+    maxPixels?: number;
 }
 
 /** Options of {@link Animation.encodeWebP}, and those all animation encoders have */
@@ -330,31 +337,46 @@ export class Animation extends Array<Frame> {
      */
     static decode(input: BinaryData, onlyExtractFirstFrame?: boolean): Promise<Animation>;
     static async decode(input: BinaryData, onlyFirstFrameOrOptions: boolean | AnimationDecodeOptions = false): Promise<Animation> {
-        const onlyExtractFirstFrame = isOptions(onlyFirstFrameOrOptions) ? onlyFirstFrameOrOptions.onlyFirstFrame ?? false : onlyFirstFrameOrOptions;
+        return decoding(() => Animation.__decode__(input, onlyFirstFrameOrOptions));
+    }
+
+    /** @internal */
+    private static async __decode__(input: BinaryData, onlyFirstFrameOrOptions: boolean | AnimationDecodeOptions): Promise<Animation> {
+        const { onlyFirstFrame: onlyExtractFirstFrame = false, maxPixels = MAX_PIXELS } = isOptions(onlyFirstFrameOrOptions) ? onlyFirstFrameOrOptions : { onlyFirstFrame: onlyFirstFrameOrOptions };
         const data = view(input);
         const type = ImageType.getType(data);
 
-        if (type === 'gif') return Animation.__fromGIF__(data, onlyExtractFirstFrame, Animation);
+        if (type === 'gif') return Animation.__fromGIF__(data, onlyExtractFirstFrame, Animation, maxPixels);
 
         if (type === 'webp') {
-            const decoded = webp.decodeAnimation(data, onlyExtractFirstFrame);
+            const decoded = webp.decodeAnimation(data, onlyExtractFirstFrame, maxPixels);
             const frames = canvasFrames(decoded.width, decoded.height, webp.composite(decoded));
             return new Animation(frames, fromPlays(decoded.loopCount));
         }
 
+        // (still PNGs decode like images, keeping their orientation as it is like before)
+        if (type === 'png' && !png.isAnimated(data)) {
+            const image = await Image.decode(data, { maxPixels, applyOrientation: false });
+            return new Animation(canvasFrames(image.width, image.height, [{ pixels: image.bitmap, duration: 0 }]), -1);
+        }
         if (type === 'png') {
-            const decoded = await png.decodeAnimation(data, onlyExtractFirstFrame);
+            const decoded = await png.decodeAnimation(data, onlyExtractFirstFrame, maxPixels);
             const frames = canvasFrames(decoded.width, decoded.height, png.compositeAnimation(decoded));
             return new Animation(frames, decoded.frames.length > 1 ? fromPlays(decoded.plays) : -1);
         }
 
-        if (type) return new Animation([Frame.from(await Image.decode(data), 0)]);
+        if (type) return new Animation([Frame.from(await Image.decode(data, { maxPixels }), 0)]);
         throw new Error('Unsupported image type');
     }
 
     /** @internal */
-    static __fromGIF__<T extends Animation>(data: Uint8Array, onlyExtractFirstFrame: boolean, Class: new (frames: Frame[], loopCount: number) => T): T {
-        const decoded = gifCodec.decode(data, onlyExtractFirstFrame);
+    static __fromGIF__<T extends Animation>(data: Uint8Array, onlyExtractFirstFrame: boolean, Class: new (frames: Frame[], loopCount: number) => T, maxPixels = MAX_PIXELS): Promise<T> {
+        return decoding(() => Animation.__gifFrames__(data, onlyExtractFirstFrame, Class, maxPixels));
+    }
+
+    /** @internal */
+    private static __gifFrames__<T extends Animation>(data: Uint8Array, onlyExtractFirstFrame: boolean, Class: new (frames: Frame[], loopCount: number) => T, maxPixels: number): T {
+        const decoded = gifCodec.decode(data, onlyExtractFirstFrame, maxPixels);
         const frames = gifCodec.composite(decoded).map(({ pixels, delay }) => ({ pixels, duration: 10 * delay }));
         return new Class(canvasFrames(decoded.width, decoded.height, frames), decoded.loopCount);
     }

diff --git a/src/codecs/gif.ts b/src/codecs/gif.ts
@@ -1,4 +1,5 @@
 import { quantize } from './quantize.ts';
+import { MAX_PIXELS, PixelBudget, checkPixels } from '../util/limits.ts';
 
 // ImageScript disposal modes (any, keep, previous, background) <-> GIF disposal methods (unspecified, none, background, previous)
 const DISPOSAL_TO_GIF = [0, 1, 3, 2];
@@ -206,7 +207,7 @@ function writeSubBlocks(out: ByteWriter, data: Uint8Array): void {
  * @param {boolean} [onlyFirstFrame=false]
  * @return {{width: number, height: number, loopCount: number, frames: GIFFrame[]}}
  */
-export function decode(data: Uint8Array, onlyFirstFrame = false): DecodedGIF {
+export function decode(data: Uint8Array, onlyFirstFrame = false, maxPixels = MAX_PIXELS): DecodedGIF {
     const reader = new ByteReader(data);
 
     const signature = reader.string(6);
@@ -222,6 +223,8 @@ export function decode(data: Uint8Array, onlyFirstFrame = false): DecodedGIF {
     const frames: DecodedGIFFrame[] = [];
     let loopCount = 0;
     let control: GraphicControl | null = null;
+    // the frames' color indices, and later a canvas per frame
+    const budget = new PixelBudget(maxPixels);
 
     try {
         parse();
@@ -230,6 +233,7 @@ export function decode(data: Uint8Array, onlyFirstFrame = false): DecodedGIF {
         if (err !== UNEXPECTED_END) throw err;
     }
 
+    checkPixels(width, height, maxPixels, Math.max(1, frames.length));
     return { width, height, loopCount, frames };
 
     function parse(): void {
@@ -287,6 +291,7 @@ export function decode(data: Uint8Array, onlyFirstFrame = false): DecodedGIF {
 
             const minCodeSize = reader.u8();
             const compressed = readSubBlocks(reader);
+            budget.take(fw, fh);
             const indices = lzwDecode(compressed, minCodeSize, fw * fh);
 
             const { dispose = 0, delay = 0, transparentIndex = -1 } = control || {};

diff --git a/src/codecs/jpeg.ts b/src/codecs/jpeg.ts
@@ -5,6 +5,7 @@
  * (Copyright 2014 Mozilla Foundation, Apache License 2.0). See THIRD_PARTY_NOTICES.md
  */
 
+import { MAX_PIXELS, checkPixels } from '../util/limits.ts';
 import { orientation as exifOrientation } from './exif.ts';
 import { concat } from '../util/mem.ts';
 
@@ -60,6 +61,8 @@ interface Frame {
 export interface DecodeOptions {
     /** overrides the color transform detected from JFIF/Adobe markers (used by TIFF) */
     transform?: 'ycc' | 'rgb' | 'cmyk' | null;
+    /** the most pixels to decode */
+    maxPixels?: number;
 }
 
 function clamp8(v: number): number {
@@ -79,7 +82,7 @@ function clamp8(v: number): number {
  * @param {{transform?: 'ycc'|'rgb'|'cmyk'}} [options] overrides the color transform detected from JFIF/Adobe markers (used by TIFF)
  * @return {{width: number, height: number, pixels: Uint8Array}}
  */
-export function decode(data: Uint8Array, { transform }: DecodeOptions = {}): { width: number, height: number, pixels: Uint8Array, orientation: number } {
+export function decode(data: Uint8Array, { transform, maxPixels = MAX_PIXELS }: DecodeOptions = {}): { width: number, height: number, pixels: Uint8Array, orientation: number } {
     if (data[0] !== 0xff || data[1] !== 0xd8) throw new Error('JPEG: invalid signature');
 
     const quantizationTables: Int32Array[] = [];
@@ -160,6 +163,7 @@ export function decode(data: Uint8Array, { transform }: DecodeOptions = {}): { w
             case 0xc0: case 0xc1: case 0xc2: { // SOF baseline, extended, progressive
                 if (frame) throw new Error('JPEG: multiple frames are not supported');
                 if (data[start] !== 8) throw new Error(`JPEG: ${data[start]}-bit precision is not supported`);
+                checkPixels(u16(start + 3), u16(start + 1), maxPixels);
                 frame = createFrame(marker === 0xc2, u16(start + 1), u16(start + 3), data.subarray(start + 5, end));
                 break;
             }
@@ -235,6 +239,8 @@ function createFrame(progressive: boolean, height: number, width: number, compon
     }
 
     if (!width || !sampling.length) throw new Error('JPEG: invalid dimensions');
+    // each component takes coefficients for the whole image (grey, YCbCr/RGB and CMYK have up to 4)
+    if (sampling.length > 4) throw new Error(`JPEG: ${sampling.length} components are not supported`);
 
     const hmax = Math.max(...sampling.map(c => c.h));
     const vmax = Math.max(...sampling.map(c => c.v));

diff --git a/src/codecs/png.ts b/src/codecs/png.ts
@@ -1,4 +1,5 @@
 import { crc32 } from './crc.ts';
+import { MAX_PIXELS, checkPixels } from '../util/limits.ts';
 import { concat } from '../util/mem.ts';
 import { encode as utf8, decode as utf8Decode } from '../util/utf8.ts';
 import { orientation as exifOrientation, xmpOrientation } from './exif.ts';
@@ -559,7 +560,7 @@ async function decodeImageData(p: Parsed, chunks: Uint8Array[], width: number, h
 
         const rowBytes = Math.ceil(pw * bitsPerPixel / 8);
         const size = ph * rowBytes;
-        const pixels = unfilter(data, dataOffset, ph, rowBytes, bpp);
+        const pixels = unfilter(data, dataOffset, ph, rowBytes, bpp, !interlace);
         dataOffset += size + ph;
 
         toRGBA(pixels, rowBytes, pw, ph, rgba, { row: y => ((ys + y * dy) * width + xs) * 4, step: dx * 4 });
@@ -574,9 +575,10 @@ async function decodeImageData(p: Parsed, chunks: Uint8Array[], width: number, h
  * The orientation comes from the eXIf chunk, or, if there is none, from the Exif text ImageMagick wrote before eXIf
  * existed ("Raw profile type exif") or from the XMP packet
  */
-export async function decode(array: Uint8Array): Promise<Decoded> {
+export async function decode(array: Uint8Array, maxPixels = MAX_PIXELS): Promise<Decoded> {
     const p = parse(array);
     const { width, height } = p.header;
+    checkPixels(width, height, maxPixels);
     const pixels = await decodeImageData(p, p.idat, width, height);
     return { width, height, pixels, orientation: p.exif ? exifOrientation(p.exif) : await textOrientation(p.text) };
 }
@@ -610,9 +612,11 @@ export function isAnimated(array: Uint8Array): boolean {
  * a single frame
  * @return plays: 0 = forever
  */
-export async function decodeAnimation(array: Uint8Array, onlyFirstFrame = false): Promise<{ width: number, height: number, plays: number, frames: APNGFrame[] }> {
+export async function decodeAnimation(array: Uint8Array, onlyFirstFrame = false, maxPixels = MAX_PIXELS): Promise<{ width: number, height: number, plays: number, frames: APNGFrame[] }> {
     const p = parse(array);
     const { width, height } = p.header;
+    // every frame is composited onto a canvas of its own
+    checkPixels(width, height, maxPixels, !p.animation || p.animationError || onlyFirstFrame ? 1 : Math.max(1, p.frames.length));
 
     // broken animations show the default image, like browsers do
     if (!p.animation || p.animationError) {
@@ -647,18 +651,29 @@ export function compositeAnimation({ width, height, frames }: { width: number, h
     for (const f of frames) {
         const previous = f.dispose === 2 ? canvas.slice() : null;
 
-        for (let y = 0; y < f.height; y++)
+        for (let y = 0; y < f.height; y++) {
+            // replacing: whole rows
+            if (f.blend === 0) {
+                canvas.set(f.pixels.subarray(y * f.width * 4, (y + 1) * f.width * 4), ((f.y + y) * width + f.x) * 4);
+                continue;
+            }
             for (let x = 0; x < f.width; x++) {
                 const s = (y * f.width + x) * 4, d = ((f.y + y) * width + f.x + x) * 4;
                 const sa = f.pixels[s + 3], da = canvas[d + 3];
-                if (f.blend === 0 || sa === 255 || da === 0) {
-                    if (f.blend === 0 || sa !== 0) canvas.set(f.pixels.subarray(s, s + 4), d);
+                if (sa === 255 || da === 0) {
+                    if (sa !== 0) {
+                        canvas[d] = f.pixels[s];
+                        canvas[d + 1] = f.pixels[s + 1];
+                        canvas[d + 2] = f.pixels[s + 2];
+                        canvas[d + 3] = sa;
+                    }
                 } else if (sa !== 0) {
                     const u = sa * 255, v = (255 - sa) * da, al = u + v;
                     for (let c = 0; c < 3; c++) canvas[d + c] = (f.pixels[s + c] * u + canvas[d + c] * v) / al | 0;
                     canvas[d + 3] = al / 255 | 0;
                 }
             }
+        }
 
         output.push({ pixels: canvas.slice(), duration: f.duration });
 
@@ -718,8 +733,10 @@ function hexProfile(text: string): Uint8Array {
     return out;
 }
 
-function unfilter(data: Uint8Array, offset: number, height: number, rowBytes: number, bpp: number): Uint8Array {
-    const out = new Uint8Array(height * rowBytes);
+// undoes the row filters; in place writes the rows over the data itself (every row ends up before where its data was,
+// and the data is read ahead of what's written)
+function unfilter(data: Uint8Array, offset: number, height: number, rowBytes: number, bpp: number, inPlace = false): Uint8Array {
+    const out = inPlace ? data.subarray(offset, offset + height * rowBytes) : new Uint8Array(height * rowBytes);
     const first = Math.min(bpp, rowBytes);
 
     // the first row and the first pixel of every row have zero neighbours, those are handled by separate loops

diff --git a/src/codecs/tga.ts b/src/codecs/tga.ts
@@ -1,4 +1,5 @@
 import { encode as utf8 } from '../util/utf8.ts';
+import { MAX_PIXELS, checkPixels } from '../util/limits.ts';
 
 // Truevision TGA: color mapped, truecolor and greyscale images, uncompressed or run length encoded
 
@@ -91,10 +92,11 @@ function readColor(d: Uint8Array, o: number, bits: number, alphaBits: number, ou
 /**
  * Decodes a TGA into RGBA
  */
-export function decode(d: Uint8Array): { width: number, height: number, pixels: Uint8Array } {
+export function decode(d: Uint8Array, maxPixels = MAX_PIXELS): { width: number, height: number, pixels: Uint8Array } {
     const h = readHeader(d);
     if (!h || !isTGA(d)) throw new Error('TGA: invalid header');
     const { width, height, depth } = h;
+    checkPixels(width, height, maxPixels);
     const base = h.imageType & ~8, rle = (h.imageType & 8) !== 0;
     const bytesPerPixel = Math.ceil(depth / 8);
 

diff --git a/src/codecs/tiff.ts b/src/codecs/tiff.ts
@@ -1,5 +1,6 @@
 import { decompressAsync } from './zlib.ts';
 import * as jpeg from './jpeg.ts';
+import { MAX_PIXELS, checkPixels, checkBytes } from '../util/limits.ts';
 
 const TYPE_SIZES: Record<number, number> = { 1: 1, 2: 1, 3: 2, 4: 4, 5: 8, 6: 1, 7: 1, 8: 2, 9: 4, 10: 8, 11: 4, 12: 8, 13: 4, 16: 8, 17: 8, 18: 8 };
 
@@ -46,7 +47,7 @@ interface SampleReader {
     (rowOffset: number, n: number): { raw: number, value: number };
 }
 
-export async function decode(data: Uint8Array): Promise<{ width: number, height: number, pixels: Uint8Array, orientation: number }> {
+export async function decode(data: Uint8Array, maxPixels = MAX_PIXELS): Promise<{ width: number, height: number, pixels: Uint8Array, orientation: number }> {
     const view = new DataView(data.buffer, data.byteOffset, data.byteLength);
 
     let little: boolean;
@@ -178,6 +179,11 @@ export async function decode(data: Uint8Array): Promise<{ width: number, height:
         return data.subarray(offset, Math.min(data.length, offset + count));
     };
 
+    checkPixels(width, height, maxPixels);
+    // tiles may reach past the image, but not by much (a segment's buffer is that large), and samples can take more
+    // memory than the pixels
+    checkPixels(segmentWidth, segmentHeight, Math.max(4 * width * height, 1 << 20));
+    checkBytes(Math.ceil(width * samplesPerPixel * bps / 8) * height, maxPixels);
     const pixels = new Uint8Array(width * height * 4);
 
     // JPEG compressed segments decode straight to RGBA