Add support for auto conversion to RGB

src/ol/source/GeoTIFF.js

@@ -5,6 +5,7 @@ import DataTile from './DataTile.js';
 import TileGrid from '../tilegrid/TileGrid.js';
 import {
   Pool,
+  globals as geotiffGlobals,
   fromBlob as tiffFromBlob,
   fromUrl as tiffFromUrl,
   fromUrls as tiffFromUrls,
@@ -31,6 +32,31 @@ function isMask(image) {
   return (type & 4) === 4;
 }
 
+/**
+ * @param {true|false|'auto'} preference The convertToRGB option.
+ * @param {GeoTIFFImage} image The image.
+ * @return {boolean} Use the `image.readRGB()` method.
+ */
+function readRGB(preference, image) {
+  if (!preference) {
+    return false;
+  }
+  if (preference === true) {
+    return true;
+  }
+  if (image.getSamplesPerPixel() !== 3) {
+    return false;
+  }
+  const interpretation = image.fileDirectory.PhotometricInterpretation;
+  const interpretations = geotiffGlobals.photometricInterpretations;
+  return (
+    interpretation === interpretations.CMYK ||
+    interpretation === interpretations.YCbCr ||
+    interpretation === interpretations.CIELab ||
+    interpretation === interpretations.ICCLab
+  );
+}
+
 /**
  * @typedef {Object} SourceInfo
  * @property {string} [url] URL for the source GeoTIFF.
@@ -320,9 +346,10 @@ function getMaxForDataType(array) {
  * another with 1 band, the resulting data tiles will have 5 bands: 3 from the first source, 1 alpha
  * band from the first source, and 1 band from the second source.
  * @property {GeoTIFFSourceOptions} [sourceOptions] Additional options to be passed to [geotiff.js](https://geotiffjs.github.io/geotiff.js/module-geotiff.html)'s `fromUrl` or `fromUrls` methods.
- * @property {boolean} [convertToRGB = false] By default, bands from the sources are read as-is. When
+ * @property {true|false|'auto'} [convertToRGB=false] By default, bands from the sources are read as-is. When
  * reading GeoTIFFs with the purpose of displaying them as RGB images, setting this to `true` will
- * convert other color spaces (YCbCr, CMYK) to RGB.
+ * convert other color spaces (YCbCr, CMYK) to RGB.  Setting the option to `'auto'` will make it so CMYK, YCbCr,
+ * CIELab, and ICCLab images will automatically be converted to RGB.
  * @property {boolean} [normalize=true] By default, the source data is normalized to values between
  * 0 and 1 with scaling factors based on the raster statistics or `min` and `max` properties of each source.
  * If instead you want to work with the raw values in a style expression, set this to `false`.  Setting this option
@@ -424,9 +451,9 @@ class GeoTIFFSource extends DataTile {
     this.error_ = null;
 
     /**
-     * @type {'readRasters' | 'readRGB'}
+     * @type {true|false|'auto'}
      */
-    this.readMethod_ = options.convertToRGB ? 'readRGB' : 'readRasters';
+    this.convertToRGB_ = options.convertToRGB || false;
 
     this.setKey(this.sourceInfo_.map((source) => source.url).join(','));
 
@@ -747,7 +774,7 @@ class GeoTIFFSource extends DataTile {
         }
       }
 
-      requests[sourceIndex] = image[this.readMethod_]({
+      const readOptions = {
         window: pixelBounds,
         width: sourceTileSize[0],
         height: sourceTileSize[1],
@@ -755,7 +782,12 @@ class GeoTIFFSource extends DataTile {
         fillValue: fillValue,
         pool: pool,
         interleave: false,
-      });
+      };
+      if (readRGB(this.convertToRGB_, image)) {
+        requests[sourceIndex] = image.readRGB(readOptions);
+      } else {
+        requests[sourceIndex] = image.readRasters(readOptions);
+      }
 
       // requests after `sourceCount` are for mask data (if any)
       const maskIndex = sourceCount + sourceIndex;

test/browser/spec/ol/source/GeoTIFF.test.js

@@ -3,7 +3,7 @@ import TileState from '../../../../../src/ol/TileState.js';
 
 describe('ol/source/GeoTIFF', function () {
   describe('constructor', function () {
-    it('configures readMethod_ to read rasters', function () {
+    it('sets convertToRGB false by default', function () {
       const source = new GeoTIFFSource({
         sources: [
           {
@@ -11,10 +11,10 @@ describe('ol/source/GeoTIFF', function () {
           },
         ],
       });
-      expect(source.readMethod_).to.be('readRasters');
+      expect(source.convertToRGB_).to.be(false);
     });
 
-    it('configures readMethod_ to read RGB', function () {
+    it('respects the convertToRGB option', function () {
       const source = new GeoTIFFSource({
         convertToRGB: true,
         sources: [
@@ -23,7 +23,19 @@ describe('ol/source/GeoTIFF', function () {
           },
         ],
       });
-      expect(source.readMethod_).to.be('readRGB');
+      expect(source.convertToRGB_).to.be(true);
+    });
+
+    it('accepts auto convertToRGB', function () {
+      const source = new GeoTIFFSource({
+        convertToRGB: 'auto',
+        sources: [
+          {
+            url: 'spec/ol/source/images/0-0-0.tif',
+          },
+        ],
+      });
+      expect(source.convertToRGB_).to.be('auto');
     });
 
     it('defaults to wrapX: false', function () {

test/rendering/cases/cog-rgb-auto/main.js

@@ -0,0 +1,22 @@
+import GeoTIFF from '../../../../src/ol/source/GeoTIFF.js';
+import Map from '../../../../src/ol/Map.js';
+import TileLayer from '../../../../src/ol/layer/WebGLTile.js';
+
+const source = new GeoTIFF({
+  convertToRGB: 'auto',
+  sources: [{url: '/data/raster/masked.tif'}],
+});
+
+new Map({
+  layers: [
+    new TileLayer({
+      source: source,
+    }),
+  ],
+  target: 'map',
+  view: source.getView(),
+});
+
+render({
+  message: 'automatically converts to rgb',
+});

test/rendering/cases/cog-rgb-no-auto/main.js

@@ -0,0 +1,22 @@
+import GeoTIFF from '../../../../src/ol/source/GeoTIFF.js';
+import Map from '../../../../src/ol/Map.js';
+import TileLayer from '../../../../src/ol/layer/WebGLTile.js';
+
+const source = new GeoTIFF({
+  convertToRGB: false,
+  sources: [{url: '/data/raster/masked.tif'}],
+});
+
+new Map({
+  layers: [
+    new TileLayer({
+      source: source,
+    }),
+  ],
+  target: 'map',
+  view: source.getView(),
+});
+
+render({
+  message: 'can be overridden to read raw YCbCr',
+});