[Kickaha]

Alright, I feel old. I knew how to do this about a decade ago.

I want to reduce the number of colors in an image to just a handful - in the dark ages, I'd just scale the bits per pixel down to 4 or 5, and get a nice small color map. Now, I'm looking at Pixelmator (Photoshop analogue) and going "Whaaaaaaa?"

Help the geezer out. What's the best way to:

1) Reduce the color map.
2) Reduce the resolution. The Pixellate filter works nicely for this one, but if someone has an alternative, I'm all ears.

Goal: reduction of an image to something suitable for my wife to cross-stitch it. Think NES graphics. Blocky, 16 colors.

[Dave]

Can Graphics Converter do that? Lemmie install my copy of it and I'll tell you.

[Kickaha]

I thought of that too, but my wife said she futzed with it and couldn't get it to produce something she was happy with. (I don't have it on my machine.)

What with all the gee-whiz CoreWhatchamacallits, you'd think this would be simple.

[Dave]

GraphicConverter X 6.1 does it just fine on my comp. Of course, we're not working on the same image.

[drewprops]

Well of course you know there are twexty farkullion of us with Photoshop.... just say the word and we can edit the image for you, snappity snap-snap. Otherwise, I'm in the dark.

Oh, but not if it's family porn.

[Kickaha]

Damn.

Just kidding.

They're just friends.




ANYwho... been playing around with it, and getting her opinion, and I found out the problem. Sure, you can minimize it down to 16 colors, but the dithering would make stitching it HELLISH. What she's looking for is something that makes more solid areas of single colors where possible. CoreImage's Posterize is similar in nature, but the colors are just wrong wrong wrong. Tried edge detection (nope), and a couple other things. The closest I came up with was the CoreImage Gloom filter, which gave a nice soft look to the photo prior to reducing the color table. That helped a lot, but not quite enough.

[Swox]

For #2: Wouldn't the easiest way be to just reduce the number of pixels per square inch (Image - Image size)? Isn't an embroidered image basically a really low pixel per inch image? You could even count the number of stitches per inch that she's doing and make it the same resolution.

For #1: Does Image - Mode - Indexed Color - 16 colors do it for you? You can play with the number for different results.

[Kickaha]

Yes on the first, not so much on the second. The colors that it picks are what are best for dithering into a faithful color representation of the image, not what's best for contiguous representation of the areas and lines.

I've been playing with both, with mixed results.

[Swox]

Have you been playing with the Image - Mode - Color Table? You could be pretty specific there about the colours you want.

I got this with the following settings: Colors: 30, dithering 1%; Image size: 6x4, 20 pixels/inch sq. (You'll need to blow it up a lot to see the results)

http://i169.photobucket.com/albums/u...orKickacha.png

[Dave]

Have you tried turning off dithering? I've been messing around with an image I've got on my machine with mixed results.

[709]

Originally Posted by Swox For #1: Does Image - Mode - Indexed Color - 16 colors do it for you? You can play with the number for different results.

This combined with the Mosaic filter works pretty well (I think):

Original:



Mosaic Filter w/ 4px cell size:



Mode: Index Color - 16 colors:




It doesn't even look too bad at 8 colors:




You can play with specific thread colors as well in the Index Color conversion.

[curiousuburb]

Originally Posted by Kickaha ANYwho... been playing around with it, and getting her opinion, and I found out the problem. Sure, you can minimize it down to 16 colors, but the dithering would make stitching it HELLISH. What she's looking for is something that makes more solid areas of single colors where possible. CoreImage's Posterize is similar in nature, but the colors are just wrong wrong wrong. Tried edge detection (nope), and a couple other things. The closest I came up with was the CoreImage Gloom filter, which gave a nice soft look to the photo prior to reducing the color table. That helped a lot, but not quite enough.

Got Flash or Illustrator?

Sounds like a vectorization tool built for defining stroke and fill areas could help.

Alternatively, what about pushing the curves or levels of the image or doing some replace colour before getting to the 16 or 8 colour table instead of after?

Post the image and some examples of good result versus bad result from embroiderama.com or whatever benchmark she's set.

[tomoe]

If you've got Matlab, this is really easy to do. You can specify precisely how many colors to use. Failing access to Matlab, Octave is free and should also be able to do it just as easily.

[Kickaha]

709, that's exactly the look we're going for. I take it that's Photoshop?

[709]

Yeah, I tried to do it in Pixelmator first, but I couldn't for the life of me find a way to go from the Pixellate filter to Index Color. The Mosaic filter in Photoshop seemed to do a better job than the Pixellate filter in Pixelmator, too. I haven't really played around enough in Pixelmator to know it very well, so I may be missing something obvious.