fix: rendering of palette color for no useRGB flag (#459)

Author: sedghi

src/imageLoader/createImage.js

@@ -198,39 +198,59 @@ function createImage(imageId, pixelData, transferSyntax, options = {}) {
       const isColorImage = isColorImageFn(imageFrame.photometricInterpretation);
 
       if (isColorImage) {
-        // JPEGBaseline (8 bits) is already returning the pixel data in the right format (rgba)
-        // because it's using a canvas to load and decode images.
-        if (!isJPEGBaseline8BitColor(imageFrame, transferSyntax) && useRGBA) {
-          canvas.height = imageFrame.rows;
-          canvas.width = imageFrame.columns;
+        if (useRGBA) {
+          // JPEGBaseline (8 bits) is already returning the pixel data in the right format (rgba)
+          // because it's using a canvas to load and decode images.
+          if (!isJPEGBaseline8BitColor(imageFrame, transferSyntax)) {
+            canvas.height = imageFrame.rows;
+            canvas.width = imageFrame.columns;
+
+            const context = canvas.getContext('2d');
+
+            const imageData = context.createImageData(
+              imageFrame.columns,
+              imageFrame.rows
+            );
 
-          const context = canvas.getContext('2d');
+            convertColorSpace(imageFrame, imageData.data, useRGBA);
 
-          const imageData = context.createImageData(
-            imageFrame.columns,
-            imageFrame.rows
-          );
+            imageFrame.imageData = imageData;
+            imageFrame.pixelData = imageData.data;
+          }
+        } else {
+          if (isJPEGBaseline8BitColor(imageFrame, transferSyntax)) {
+            // If we don't need the RGBA but the decoding is done with RGBA (the case
+            // for JPEG Baseline 8 bit color), AND the option specifies to use RGB (no RGBA)
+            // we need to remove the A channel from pixel data
+            const colorBuffer = new Uint8ClampedArray(
+              (imageFrame.pixelData.length / 4) * 3
+            );
 
-          convertColorSpace(imageFrame, imageData.data, useRGBA);
-
-          imageFrame.imageData = imageData;
-          imageFrame.pixelData = imageData.data;
-        } else if (
-          isJPEGBaseline8BitColor(imageFrame, transferSyntax) &&
-          !useRGBA
-        ) {
-          // If we don't need the RGBA but the decoding is done with RGBA (the case
-          // for JPEG Baseline 8 bit color), AND the option specifies to use RGB (no RGBA)
-          // we need to remove the A channel from pixel data
-          const newPixelData = new imageFrame.pixelData.constructor(
-            (imageFrame.pixelData.length / 4) * 3
-          );
+            // remove the A from the RGBA of the imageFrame
+            imageFrame.pixelData = removeAFromRGBA(
+              imageFrame.pixelData,
+              colorBuffer
+            );
+          } else if (imageFrame.photometricInterpretation === 'PALETTE COLOR') {
+            canvas.height = imageFrame.rows;
+            canvas.width = imageFrame.columns;
 
-          // remove the A from the RGBA of the imageFrame
-          imageFrame.pixelData = removeAFromRGBA(
-            imageFrame.pixelData,
-            newPixelData
-          );
+            const context = canvas.getContext('2d');
+
+            const imageData = context.createImageData(
+              imageFrame.columns,
+              imageFrame.rows
+            );
+
+            convertColorSpace(imageFrame, imageData.data, true);
+
+            const colorBuffer = new imageData.data.constructor(
+              (imageData.data.length / 4) * 3
+            );
+
+            // remove the A from the RGBA of the imageFrame
+            imageFrame.pixelData = removeAFromRGBA(imageData.data, colorBuffer);
+          }
         }
 
         // calculate smallest and largest PixelValue of the converted pixelData