Can image events add a layer to a png file?

One option is ImageMagick which you can run from Terminal or use in a script. For example, to add the background color #e8e8e8 to a PNG image with a transparent background and output a flattened PNG image file you can use the following command:

magick image_in.png -background "#e8e8e8" -flatten image_out.png

image_in.png:

image_out.png:

To output a flattened JPEG image file you can use the following command:

magick image_in.png -background "#e8e8e8" -flatten image_out.jpg

Roote,

I wondered about ImageMagick, but did not have it installed to test, so good find. The Inkscape command-line can also output png with a background argument, but I also removed XQuartz and Inkscape, so couldn't test that either.

Hi Viking. Here's something you can test since macOS comes bundled with PHP. I'm not that familiar with PHP but I recall that PHP contains the GD library of image functions. I did some research on php.net and cobbled a solution together by mashing a couple of scripts from comments on Stack Overflow. The script:

#!/usr/bin/env php

<?php

/* 
 * Modification of a script by Mark Setchell
 * from https://stackoverflow.com/a/39272442
 * Hex to RGB conversion by John
 * from https://stackoverflow.com/a/15202130
 */

// Get source PNG image with transparency
$src = imagecreatefrompng('/Users/<short username>/Desktop/image_in.png');

// Get width and height of source PNG image
$w = imagesx($src);
$h = imagesy($src);

// Convert hex color values to RGB values
$hex = "#e8e8e8";
list($r, $g, $b) = sscanf($hex, "#%02x%02x%02x");

// Create a background canvas, same size, to overlay onto
$im = imagecreatetruecolor($w, $h);
$bg = imagecolorallocate($im, $r, $g, $b);
imagefill($im, 0, 0, $bg);

// Overlay source PNG image on top of canvas
imagecopyresampled($im, $src, 0, 0, 0, 0, $w, $h, $w, $h);

// Save flattened source and background image file
imagepng($im, '/Users/<short username>/Desktop/image_out.png', 0);
?>

I tested by running the script from Terminal:

php -f '/Users/<short username>/Desktop/add_background.php'

Or...

./add_background.php ./image_in.png ./image_out.png

Changes:

// $src = imagecreatefrompng('/Users/<short username>/Desktop/image_in.png');
$src = imagecreatefrompng($argv[1]);
$out_png = $argv[2];

// imagepng($im, '/Users/<short username>/Desktop/image_out.png', 0);
imagepng($im, $out_png, 0);

Good suggestion, makes running the script practical.

However, there are issues with the output from GD as implemented in the script that would need to be resolved to move from an exploratory to a viable solution. For instance, one issue is the ballooning file size. The PNG source image is 1.6 MB approx. ImageMagick outputs 1.6 MB while GD outputs 8.6 MB. GD also strips the color profile and DPI value. ImageMagick retains both from the source image.

There is nothing in the Image Events AppleScript dictionary that supports layers, or background color capability.

Nothing else comes to mind without GUI application activity.

Yes, the PHP script works just fine. Because you are using the shebang within the script, you can run it from the command-line as:

./add_background.php

Even better, thanks.