How to create a “painting by number” picture in photoshop?

Question

I know this question is very counter intuitive.

Well, Photoshop is used to alter pictures and I guess there is no way that they can detect, for example where a building ends, or where the outline of a person is, can it?

I just want the place, where something ends, not all the shades in between.

For example, on a cartooney caracter like Donald Duck, so that I only have the lines, and then could color the figure.

How can I get the outline of this :

This question is not like this one:

What software can create a paint-by-number?

where they use a 3rd party plugin. I'd like to know how you do it in photoshop, but not that I'd be tracking everything by hand.

More that I just get the contours.

Feel free to alter this question, if you beleve that it claryfies it.

Answer 1

This will be hard work in Photoshop, but fairly straightforward if you have access to Adobe Illustrator...

In Illustrator, you can use the Image Trace function to turn an image into paths. This used to be fairly unreliable, but the functionality in newer versions of Illustrator is pretty awesome.

The trick is to trace the image into a full colour trace and then selectively remove the colour and add outlines. In the below example, I used Select > Same > Fill colour to select all of the black outlines and then locked them. I then selected all of the coloured shapes and changed them to white with a black outline...

Not bad for two minutes work and it could be a lot better with a bit of time and care.

One thing to note: the higher the resolution of the source image, the better the result will be.

Answer 2

Ok, so the main difference between your picture and the owl is complexity. So the main problem is not selecting and separating values but the amount you would need to put to mark every place you need to number.
I'm assuming you want to create "paint-by-numbers" for kids so limited pallet, big shapes etc.

You will use a lot of Select>color range
So the color picker will be your friend shortcut 'I'
First you would need to select and separate the black outlines. Just use color picker to find the black color go to Select>color range and the pop-up window should show you what will be selected.
Don't be afraid to move fuzziness to 200 and select extra color as you can delete it later. Click OK and then duplicate the layer ctrl/cmd+J

Then you repeat this step for every color.

Now a cool trick for those who say

what if I miss some color?

Go to image>duplicate then choose Image > Mode > Indexed in the index color box set the desired number of colors (don't worry, if your picture don't have 256 color then they won't show). Go to Image > Mode > Color Table hit save and you have a brand new color swatch for your picture. Just load it and you can easily choose colors to select.

Now, back to our picture. I assume that by now you have every color on separate layer.
On top of layers create new layer and call it "inside outlines". Then select every layer content (but one by one) with ctrl/cmd clicking on the layer miniature. With edit>stroke create on the "inside outlines" an outline. Repeat for every color.

Now, on top of that move the first layer with the original outline. Look to see if nothing is confusing or unnecessary (like the lines on his knees). If yes then just erase them. IF your outer outline have this extra spaces with color just select corresponding layer with ctrl/cmdend use it to delete the unneeded things.

And now what is left is to number the colors. And this is manual labor.