I don't know your data but with my simple data:

use constant IMAGESIZE => 5;
my @data = (0x0)x(IMAGESIZE*IMAGESIZE);
$data[0] = 0xAA;  
$data[3] = 0xBB;
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This: convert data.png data.txt shows that it still thinks data is 4 bytes long. Imager is way too complex for me and pack even more so. Perhaps modify the code supplied by vr in Re: How to create and save an image from RGB values to get only 1 channel using the combine() thingy?

bw, bliako