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Cannot convert from rgb to monochrome
#4
Hi. Okay, to recap: I've got a PC with 32 bit system, which has insuffcient RAM (and I've got 4Gb installed) to enable GIMP to edit or otherwise deal with a jpg file that is 15380 pixels x 10511 pixels. File size 39.9Mb.

As directed, I downloaded a version of Image Magic. I chose Windows version - ImageMagick-7.0.7-22-Q8-x86-static.exe. (8 bit)

That was chosen because my image is a simple map.  Not many colours in it, in fact greyscale is fine.

Opening up a command prompt (actually I did an elevated prompt) I navigated to the directory where my large file is.  Then I wrote at the command prompt (substituting the actual filename instead of "something.jpg"):


Code:
magick convert something.jpg -colorspace gray new.jpg

I then opened up the newly created file (I actually called it "new.jpg"). And I used the threshold tool to remove colouration.  And it worked. I now have a cleaned up image of the map. Some discolouration, which was an eyesore, has been removed. But the whole map is cleaner.

Interesting the new file is actually bigger than the original file at 56.5Mb - according to windows. But, GIMP seems to be handling it.  Thanks.

P.S. The original file apparantly is a lut style RGB XYZ input profle. I cannot remember if I converted it or kept it when opening the file. Nor know whether I should have converted or not. Oh, but that's not relevant, because I converted the file with Image Magic. :-)
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RE: Cannot convert from rgb to monochrome - by richard5588 - 02-14-2018, 09:05 PM

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