PHP将原始RGBA保存为PNG / GIF

Question

I have an image file, with a 128 byte header, followed by raw RGBA data and the width and height are stored at offset 72 and 74 as short ints (big endian). I have successfully been able to read the header, however, I need a way to save the raw RGBA as PNG format and/or GIF. How can I do that in PHP?

cheers

Answer 1

If you have the gd lib installed (check with phpinfo(); ) it's something like

//create image
$img = imagecreatetruecolor($width, $height);

//fill by iterating through your raw pixel data
imagesetpixel($img, $x, $y, $color);

//output
header("Content-Type: image/png");
imagepng($img);

//cleanup
imagedestroy($img);

EDIT

You said it was RGBA data. Assuming standard 4 bytes per channel and that your raw data is an integer array, it should be:

$pos = ($y * $width + $x) * 4 + ($headerLengthInBytes / 4);
$red = $rawImageData[$pos];
$green = $rawImageData[$pos + 1];
$blue = $rawImageData[$pos + 2];
$alpha = $rawImageData[$pos + 3];