How to change white background to transparent using PHP (GD)?

Question

PHP

Good afternoon!
The task is to put your background under the images on a white background. The new background will be light, so if there are light (!= white) pixels around the image, it's okay.

In general, the plan is:

1. I create a copy of the image but in png format
   
2. I'm looking for white (#EEEEEE - #FFFFFF) pixels on it
   
3. I delete them, or change them to transparent
   
4. The resulting image is applied as a mask to the background.
   

But I can't find a solution to the 3rd point. Tell me how to change the white background to transparent using PHP (GD)?

Answer 1

imagecolorat - get the color of a pixel
imagesetpixel - set the color of a pixel
imagecolorallocatealpha - to create an empty color
imagealphablending - set the blending mode
imagesavealpha - save with transparency