Canvas getImageData().data return half image

Question

I'm trying to generate a pixelated canvas from image source - but there is a strange behavior of the getImageData() function - on images that are higher than my canvas I keep getting only the max height data [square of max-height * max-height]. is there anything I'm missing here?

function generatePixels(){
    const pixel_size = 10;
    const x = 0; const y = 0;
    const w = temp_ctx.canvas.width;
    const h = temp_ctx.canvas.height;

    let min_width = w,
    min_height = h,
    max_width = 0, max_height = 0;

    for (var j = y; j < (y+h); j += pixel_size) {
        for (var i = x; i < (x+w); i += pixel_size) {

            // get current pixel image data (x,y,10,10);
            var data = temp_ctx.getImageData(j, i, pixel_size, pixel_size).data;

            // draw pixel on rendered canvas 
            rendered_ctx.fillStyle = '#' + (data[2] | (data[1] << 8) | (data[0] << 16) | (1 << 24)).toString(16).slice(1);
            rendered_ctx.fillRect((j + pixel_size), (i + pixel_size), 10, 10);

      }
    }
}

You can find an example of the code here: https://codepen.io/AceDesigns/pen/dZEmjZ

Answer 1

Please find the workable code below. The issue is with the for loop condition.

for (var j = y; j < (y+h); j += pixel_size) { for (var i = x; i < (x+w); i += pixel_size) {