PHP - Replace colour within image

Question

I hope someone can help,

I have made a script that masks images... however it is reliant on a colour to mask with ( \'green screen\' style). The trouble is if the im

Answer 1

Here is the replace colour solution that first converts to 256 pallet:

//Open Image
$Image = imagecreatefromJPEG('input.jpg') or die('Problem with source');

//set the image to 256 colours
imagetruecolortopalette($Image,0,256);

//Find the Chroma colour
$RemChroma = imagecolorexact( $Image,  0,0,255 );

//Replace Chroma Colour
imagecolorset($Image,$RemChroma,0,0,254);

//Use function to convert back to true colour
imagepalettetotruecolor($Image);




function imagepalettetotruecolor(&$img)
    {
        if (!imageistruecolor($img))
        {
            $w = imagesx($img);
            $h = imagesy($img);
            $img1 = imagecreatetruecolor($w,$h);
            imagecopy($img1,$img,0,0,0,0,$w,$h);
            $img = $img1;
        }
    }

I personally prefer radio4fans solution as it is lossless, but if speed is your goal this is superior.