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feat: add support for CMYK color mode #230

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quarksb wants to merge 1 commit into from
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feat: add support for CMYK color mode #230

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2 changes: 2 additions & 0 deletions .gitignore
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Original file line number Diff line number Diff line change
Expand Up @@ -14,3 +14,5 @@
.v8-cache
TODO.md
.idea

.DS_Store
25 changes: 15 additions & 10 deletions src/psdReader.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ interface ChannelInfo {
length: number;
}

export const supportedColorModes = [ColorMode.Bitmap, ColorMode.Grayscale, ColorMode.RGB, ColorMode.Indexed];
export const supportedColorModes = [ColorMode.Bitmap, ColorMode.Grayscale, ColorMode.RGB, ColorMode.Indexed, ColorMode.CMYK];
const colorModes = ['bitmap', 'grayscale', 'indexed', 'RGB', 'CMYK', 'multichannel', 'duotone', 'lab'];

function setupGrayscale(data: PixelData) {
Expand Down Expand Up @@ -635,7 +635,7 @@ function readLayerChannelImageData(reader: PsdReader, psd: Psd, layer: Layer, ch
if (cmyk) {
const cmykData = imageData;
imageData = createImageData(cmykData.width, cmykData.height);
cmykToRgb(cmykData, imageData, false);
cmykToRgb(cmykData, imageData);
}

if (reader.useImageData) {
Expand Down Expand Up @@ -802,10 +802,14 @@ function readImageData(reader: PsdReader, psd: Psd) {
break;
}
case ColorMode.CMYK: {
if (bitsPerChannel !== 8) throw new Error('bitsPerChannel Not supproted');
if (psd.channels !== 4) throw new Error(`Invalid channel count`);
if (bitsPerChannel !== 8) throw new Error('bitsPerChannel Not supported');
// there is additional color channel for cmyk when channels === 5
if (psd.channels !== 4 && psd.channels !== 5) throw new Error(`Invalid channel count`);
// there is additional alpha channel for cmyk
const channelLen = psd.channels! + 1;

const channels = [0, 1, 2, 3];
const haveAlpha = reader.globalAlpha || psd.channels === 5;
if (reader.globalAlpha) channels.push(4);

if (compression === Compression.RawData) {
Expand All @@ -818,12 +822,12 @@ function readImageData(reader: PsdReader, psd: Psd) {
const cmykImageData: PixelData = {
width: imageData.width,
height: imageData.height,
data: new Uint8Array(imageData.width * imageData.height * 5),
data: new Uint8Array(imageData.width * imageData.height * channelLen),
};

const start = reader.offset;
readDataRLE(reader, cmykImageData, psd.width, psd.height, bitsPerChannel, 5, channels, reader.large);
cmykToRgb(cmykImageData, imageData, true);
readDataRLE(reader, cmykImageData, psd.width, psd.height, bitsPerChannel, channelLen, channels, reader.large);
cmykToRgb(cmykImageData, imageData, !haveAlpha, channelLen);

if (RAW_IMAGE_DATA) (psd as any).imageDataRaw = new Uint8Array(reader.view.buffer, reader.view.byteOffset + start, reader.offset - start);
} else {
Expand Down Expand Up @@ -860,12 +864,12 @@ function readImageData(reader: PsdReader, psd: Psd) {
}
}

function cmykToRgb(cmyk: PixelData, rgb: PixelData, reverseAlpha: boolean) {
function cmykToRgb(cmyk: PixelData, rgb: PixelData, reverseAlpha = false, channelLen = 5) {
const size = rgb.width * rgb.height * 4;
const srcData = cmyk.data;
const dstData = rgb.data;

for (let src = 0, dst = 0; dst < size; src += 5, dst += 4) {
for (let src = 0, dst = 0; dst < size; src += channelLen, dst += 4) {
const c = srcData[src];
const m = srcData[src + 1];
const y = srcData[src + 2];
Expand Down Expand Up @@ -1033,7 +1037,8 @@ export function readDataRLE(reader: PsdReader, pixelData: PixelData | undefined,

if (bitDepth !== 1 && bitDepth !== 8) throw new Error(`Invalid bit depth (${bitDepth})`);

const extraLimit = (step - 1) | 0; // 3 for rgb, 4 for cmyk
const extraLimit = (step - 1) | 0; // 3 for rgb, 4 for cmyk, 5 for cmyk+extraColor


for (let c = 0, li = 0; c < offsets.length; c++) {
const offset = offsets[c] | 0;
Expand Down