XoopsModules25x / apcal

                        }

                        // scan through current truecolor image copy alpha channel to temp image as grayscale

                        for ($x = 0; $x < $this->thumbnail_width; $x++) {

                            for ($y = 0; $y < $this->thumbnail_height; $y++) {

                                $PixelColor = phpthumb_functions::GetPixelColor($this->gdimg_output, $x, $y);

                                imagesetpixel($img_alpha_mixdown_dither, $x, $y, $dither_color[$PixelColor['alpha'] * 2]);

                            }

                        }

                        // dither alpha channel grayscale version down to 2 colors

                        imagetruecolortopalette($img_alpha_mixdown_dither, true, 2);

                        // scan through alpha channel image and note pixels with >50% transparency

                        $TransparentPixels = array();

                        for ($x = 0; $x < $this->thumbnail_width; $x++) {

                            for ($y = 0; $y < $this->thumbnail_height; $y++) {

                                $AlphaChannelPixel = phpthumb_functions::GetPixelColor($img_alpha_mixdown_dither, $x, $y);

                                if ($AlphaChannelPixel['red'] > 127) {

                                    imagesetpixel($this->gdimg_output, $x, $y, $TransparentColor);

                                }

                            }

                        }

                        imagedestroy($img_alpha_mixdown_dither);

                        $this->DebugMessage('AlphaChannelFlatten() set image to 255+1 colors with transparency for GIF output', __FILE__, __LINE__);