Add isPalette and bitsPerSample metadata, deprecate paletteBitDepth

docs/api-input.md

@@ -22,9 +22,10 @@ A `Promise` is returned when `callback` is not provided.
 - `density`: Number of pixels per inch (DPI), if present
 - `chromaSubsampling`: String containing JPEG chroma subsampling, `4:2:0` or `4:4:4` for RGB, `4:2:0:4` or `4:4:4:4` for CMYK
 - `isProgressive`: Boolean indicating whether the image is interlaced using a progressive scan
+- `isPalette`: Boolean indicating whether the image is palette-based (GIF, PNG).
+- `bitsPerSample`: Number of bits per sample for each channel (GIF, PNG, HEIF).
 - `pages`: Number of pages/frames contained within the image, with support for TIFF, HEIF, PDF, animated GIF and animated WebP
 - `pageHeight`: Number of pixels high each page in a multi-page image will be.
-- `paletteBitDepth`: Bit depth of palette-based image (GIF, PNG).
 - `loop`: Number of times to loop an animated image, zero refers to a continuous loop.
 - `delay`: Delay in ms between each page in an animated image, provided as an array of integers.
 - `pagePrimary`: Number of the primary page in a HEIF image

docs/changelog.md

@@ -6,6 +6,8 @@ Requires libvips v8.16.0-rc2
 
 ### v0.33.6 - TBD
 
+* Add `isPalette` and `bitsPerSample` to metadata, deprecate `paletteBitDepth`.
+
 * TypeScript: Ensure channel counts use the correct range.
   [#4197](https://github.com/lovell/sharp/pull/4197)
   [@DavidVaness](https://github.com/DavidVaness)

lib/index.d.ts

@@ -1076,6 +1076,10 @@ declare namespace sharp {
         chromaSubsampling?: string | undefined;
         /** Boolean indicating whether the image is interlaced using a progressive scan */
         isProgressive?: boolean | undefined;
+        /** Boolean indicating whether the image is palette-based (GIF, PNG). */
+        isPalette?: boolean | undefined;
+        /** Number of bits per sample for each channel (GIF, PNG). */
+        bitsPerSample?: number | undefined;
         /** Number of pages/frames contained within the image, with support for TIFF, HEIF, PDF, animated GIF and animated WebP */
         pages?: number | undefined;
         /** Number of pixels high each page in a multi-page image will be. */

lib/input.js

@@ -434,9 +434,10 @@ function _isStreamInput () {
  * - `density`: Number of pixels per inch (DPI), if present
  * - `chromaSubsampling`: String containing JPEG chroma subsampling, `4:2:0` or `4:4:4` for RGB, `4:2:0:4` or `4:4:4:4` for CMYK
  * - `isProgressive`: Boolean indicating whether the image is interlaced using a progressive scan
+ * - `isPalette`: Boolean indicating whether the image is palette-based (GIF, PNG).
+ * - `bitsPerSample`: Number of bits per sample for each channel (GIF, PNG, HEIF).
  * - `pages`: Number of pages/frames contained within the image, with support for TIFF, HEIF, PDF, animated GIF and animated WebP
  * - `pageHeight`: Number of pixels high each page in a multi-page image will be.
- * - `paletteBitDepth`: Bit depth of palette-based image (GIF, PNG).
  * - `loop`: Number of times to loop an animated image, zero refers to a continuous loop.
  * - `delay`: Delay in ms between each page in an animated image, provided as an array of integers.
  * - `pagePrimary`: Number of the primary page in a HEIF image

src/metadata.cc

@@ -47,8 +47,11 @@ class MetadataWorker : public Napi::AsyncWorker {
       if (image.get_typeof("interlaced") == G_TYPE_INT) {
         baton->isProgressive = image.get_int("interlaced") == 1;
       }
-      if (image.get_typeof("palette-bit-depth") == G_TYPE_INT) {
+      if (image.get_typeof(VIPS_META_PALETTE) == G_TYPE_INT) {
-        baton->paletteBitDepth = image.get_int("palette-bit-depth");
+        baton->isPalette = image.get_int(VIPS_META_PALETTE);
+      }
+      if (image.get_typeof(VIPS_META_BITS_PER_SAMPLE) == G_TYPE_INT) {
+        baton->bitsPerSample = image.get_int(VIPS_META_BITS_PER_SAMPLE);
       }
       if (image.get_typeof(VIPS_META_N_PAGES) == G_TYPE_INT) {
         baton->pages = image.get_int(VIPS_META_N_PAGES);
@@ -171,8 +174,13 @@ class MetadataWorker : public Napi::AsyncWorker {
         info.Set("chromaSubsampling", baton->chromaSubsampling);
       }
       info.Set("isProgressive", baton->isProgressive);
-      if (baton->paletteBitDepth > 0) {
+      info.Set("isPalette", baton->isPalette);
-        info.Set("paletteBitDepth", baton->paletteBitDepth);
+      if (baton->bitsPerSample > 0) {
+        info.Set("bitsPerSample", baton->bitsPerSample);
+        if (baton->isPalette) {
+          // Deprecated, remove with libvips 8.17.0
+          info.Set("paletteBitDepth", baton->bitsPerSample);
+        }
       }
       if (baton->pages > 0) {
         info.Set("pages", baton->pages);

src/metadata.h

@@ -24,7 +24,8 @@ struct MetadataBaton {
   int density;
   std::string chromaSubsampling;
   bool isProgressive;
-  int paletteBitDepth;
+  bool isPalette;
+  int bitsPerSample;
   int pages;
   int pageHeight;
   int loop;
@@ -59,7 +60,8 @@ struct MetadataBaton {
     channels(0),
     density(0),
     isProgressive(false),
-    paletteBitDepth(0),
+    isPalette(false),
+    bitsPerSample(0),
     pages(0),
     pageHeight(0),
     loop(-1),

test/unit/avif.js

@@ -34,6 +34,7 @@ describe('AVIF', () => {
       // Math.round(13.40625) = 13
       height: 13,
       isProgressive: false,
+      isPalette: false,
       space: 'srgb',
       width: 32
     });
@@ -55,6 +56,8 @@ describe('AVIF', () => {
       hasProfile: false,
       height: 26,
       isProgressive: false,
+      isPalette: false,
+      bitsPerSample: 8,
       pagePrimary: 0,
       pages: 1,
       space: 'srgb',
@@ -77,6 +80,8 @@ describe('AVIF', () => {
       hasProfile: false,
       height: 13,
       isProgressive: false,
+      isPalette: false,
+      bitsPerSample: 8,
       pagePrimary: 0,
       pages: 1,
       space: 'srgb',
@@ -100,6 +105,8 @@ describe('AVIF', () => {
       hasProfile: false,
       height: 300,
       isProgressive: false,
+      isPalette: false,
+      bitsPerSample: 8,
       pagePrimary: 0,
       pages: 1,
       space: 'srgb',
@@ -124,6 +131,8 @@ describe('AVIF', () => {
       hasProfile: false,
       height: 26,
       isProgressive: false,
+      isPalette: false,
+      bitsPerSample: 8,
       pagePrimary: 0,
       pages: 1,
       space: 'srgb',

test/unit/metadata.js

@@ -878,6 +878,8 @@ describe('Image metadata', function () {
       channels: 3,
       depth: 'uchar',
       isProgressive: false,
+      isPalette: false,
+      bitsPerSample: 8,
       pages: 1,
       pagePrimary: 0,
       compression: 'av1',

test/unit/png.js

@@ -146,6 +146,8 @@ describe('PNG', function () {
       density: 72,
       depth: 'uchar',
       isProgressive: false,
+      isPalette: true,
+      bitsPerSample: 8,
       paletteBitDepth: 8,
       hasProfile: false,
       hasAlpha: false
@@ -218,8 +220,10 @@ describe('PNG', function () {
       .png({ colours: 2, palette: false })
       .toBuffer();
 
-    const { channels, paletteBitDepth, size, space } = await sharp(data).metadata();
+    const { channels, isPalette, bitsPerSample, paletteBitDepth, size, space } = await sharp(data).metadata();
     assert.strictEqual(channels, 1);
+    assert.strictEqual(isPalette, false);
+    assert.strictEqual(bitsPerSample, 1);
     assert.strictEqual(paletteBitDepth, undefined);
     assert.strictEqual(size, 89);
     assert.strictEqual(space, 'b-w');