Create image from pixel values with Imager

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Create image from pixel values with Imager by Discipulus (Canon) on May 17, 2022 at 07:27 UTC
Hello, have you seen Re: How to create and save an image from RGB values? Can you give us more details about `slightly scrambled` results? L* There are no rules, there are no thumbs.. Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.	[reply] [d/l] [select]
Re^2: Create image from pixel values with Imager by Anonymous Monk on May 17, 2022 at 07:40 UTC
Yes I did see Re: How to create and save an image from RGB values (that's where I got the Imager code :^). Was going to mention it too but didn't, to keep things brief. By "scrambled" I mean the image is somehow partially correct, as if every other line is offset or something.	[reply]
Re^3: Create image from pixel values with Imager by kcott (Archbishop) on May 17, 2022 at 08:25 UTC
Without more information, I can only guess, but it sounds like an off-by-one error. In your OP: "65536 values from 0-254". That suggests a 255x255 square which is 65025 values; a 256x256 square is 65536 values. Do you perhaps want to start with "65536 values from 0-255"? Update: `s/off-by-error/off-by-one error/` — Ken	[reply] [d/l]
Re^4: Create image from pixel values with Imager by Anonymous Monk on May 17, 2022 at 12:39 UTC
Re^5: Create image from pixel values with Imager by Anonymous Monk on May 17, 2022 at 13:24 UTC
Re: Create image from pixel values with Imager by Anonymous Monk on May 17, 2022 at 13:12 UTC
See RAW. `raw_datachannels` default is 3. Either set it to 4, or better to 1 but then pack with `C*`.	[reply] [d/l] [select]
Re^2: Create image from pixel values with Imager by Anonymous Monk on May 17, 2022 at 13:48 UTC
Thank you so much, this works perfectly: `my $img = Imager->new( type => 'raw', xsize => 256, ysize => 256, data => pack('C*', @data), raw_interleave => 0, raw_datachannels => 1, raw_storechannels => 1 ); $img->write(file=>'data.png');` [download]	[reply] [d/l]
Re: Create image from pixel values with Imager by bliako (Monsignor) on May 17, 2022 at 14:08 UTC
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;` [download] 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	[reply] [d/l] [select]
Re: Create image from pixel values with Imager by tonyc (Friar) on Jun 07, 2022 at 12:05 UTC
Unfortunately raw_datachannels doesn't follow raw_storechannels, so if you supply one, you probably need to supply the other, this also lets you switch to pack "C" to pack the data as bytes. I don't have your data, so I can't check this does exactly what you want. `my $img = Imager->new( type => 'raw', xsize => 256, ysize => 256, data => pack('C', @data), raw_interleave => 0, raw_storechannels => 1, raw_datachannels => 1, model => 'gray' ); $img->write(file=>'data.png');` [download]	[reply] [d/l]


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