image-js
Version:
Image processing and manipulation in JavaScript
37 lines • 1.46 kB
JavaScript
/**
* Compute the mean of an image. The mean can be either computed on each channel
* individually or on the whole image.
* @param image - Image to process.
* @param options - Mean options.
* @returns The mean pixel.
*/
export function mean(image, options) {
const pixelSum = new Array(image.channels).fill(0);
const nbValues = options ? options.points.length : image.size;
if (nbValues === 0)
throw new RangeError('Array of coordinates is empty.');
if (options) {
for (const point of options.points) {
for (let channel = 0; channel < image.channels; channel++) {
if (point.column < 0 ||
point.column >= image.width ||
point.row < 0 ||
point.row >= image.height) {
throw new RangeError(`Invalid coordinate: {column: ${point.column}, row: ${point.row}}.`);
}
pixelSum[channel] += image.getValueByPoint(point, channel);
}
}
}
else {
for (let row = 0; row < image.height; row++) {
for (let column = 0; column < image.width; column++) {
for (let channel = 0; channel < image.channels; channel++) {
pixelSum[channel] += image.getValue(column, row, channel);
}
}
}
}
return pixelSum.map((channelSum) => channelSum / nbValues);
}
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