Get pixel color from an image [duplicate]

I have an image on a browser.

I want to get the top left pixel of the image color (at coordinates: 0,0), no matter whether the image is rotated or not.

How can I do that, using javascript or php code?

  • Create a canvas document.createElement
  • Get the 2d context canvas.getContext('2d')
  • Draw the image to the canvas context.drawImage(image, x, y)
    • Make sure the image is from the same domain or you won’t have access to its pixels
  • Get the pixel data for the image context.getImageData(x1, y1, x2, y2)
    • You want just the top left so context.getImageData(0, 0, 1, 1)
  • The result of getImageData will have an array of pixels in it’s data field (context.getImageData(0,0,1,1).data)
    • The array will have r, g, b and a values.

For an image on a browser you can’t use PHP unless you can transfer the image to a server first.

n the browser, if you can draw the image in a canvas you could use the getImageData() method:

var myImg = new Image();
var context = document.getElementById('canvas').getContext('2d');
context.drawImage(myImg, 0, 0);
var data = context.getImageData(x, y, 1, 1).data;

You’d have to allow for any rotation – presumably you know what rotation has been applied.

The answers/resolutions are collected from stackoverflow, are licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0 .
Read More:   Angular UI Grid 'gridApi.infiniteScroll.on.needLoadMoreData' doesn't work with changes in data

Similar Posts