For this tutorial, you will need the image/es you want to turn into a “Paint by Numbers”. This technique is intended for simple image. In some cases, if the image you chose is complex it may be difficult to add the numbers to the outlined portions and it will be better to use the “Greyscale” option instead.
1 - In Photoshop “Open” the image you want to work with.
2 - Go to Image > Auto Tone (or you can choose the Auto Contrast or Auto Color options) to fix its colors a bit.
3 - Go to Image > Mode > Indexed Color. Choose the number of colors you want to work with (remember that if you use too many, the “Greyscale” option may not work). You may need to experiment with the different options until you find the one that works better but remember to use “None” as the “Dither” option.
4 - Once you are done, go to Image > Mode RGB.
5 - Right-Click on top of the “Background” Thumbnail and choose “Duplicate Layer”. Click “OK” on the Pop Up and create a second duplicate.
6 - Select the Top-most duplicate and go to Image > Adjustments > Desaturate (Shift + Command/Control + U).
7 - Go to View > Snap and make sure it has a checkmark next to it (left side). Then go to View > Show > Grid (Command/Control + ,) to show the “Grid”.
8 - Go to Photoshop > Preferences > Guides, Grids & Slices. In the “Grids” tab use a “Gridline Every 2 centimeters” and “Subdivisions: 1”.
9 - Go to Image > Canvas Size, increase the “Height” value by 2 cm and the Bottom Center Point to “Anchor” the image. Click “OK”. This will create the space for the color guide.
10 - “Hide” the Top and Bottom layers by clicking on the Small eye icon on the left side of their Thumbnails.
11 - Use the “Magic Wand” (W) making sure the “Tolerance” value is 0 and that only the “Sample All Layers” is checked and select one of the colors.
12 - With the “Eyedropper Tool” (I), select the color as ·Foreground”.
13 - “Swap Foreground and Background Colors” (X), turn on the “Greys” layer and sample (as the “Background” swatch) the shade of grey that corresponds to the color you picked before.
14 - Use the “Rectangular Marquee Tool” (M) to create a small (2 x 2 cm) “Square” in the space you left at the top and with the “Paint Bucket Tool” (G) fill it with the sampled color. “Swap Foreground and Background Colors” (X), create another Square under the first one and fill it with the corresponding Grey shade.
15 - Repeat with the rest of the colors. Rename the Layers “Colors”, “Greys”.
16 - Assign a number to each Color Square and use the same one on its corresponding Shade of Grey.
17 - “Create a New Layer” by clicking on the small button at the bottom of the “Layers Panel”. Name the new layer “Lines”. Make sure it is placed on top of the other ones.
18 - Hide” the layers by clicking on the Small eye icon on the left side of their Thumbnails and leave only the “Colors” layer on. Use the “Magic Wand Tool” (W) to select one of the Colors, then head to Select > Modify > Border and use a 1 px value in the Pop-Up window.
19 - Make sure that you are working on the “Lines” layer and that Black is set as “Foreground” color. You can try using the “Paint Bucket Tool” to create an outline for that color but you need to make sure that you are painting all of the selected areas.
20 - You can also use the “Brush Tool” (B) with a Large Brush (1000 px) to paint the selection instead. Repeat with all the colors.
21 - Create a “New Solid Color Adjustment Layer” by clicking on the small Black and White circle at the bottom of the “Layers Panel” and fill it with White #ffffff. Place this layer between the “Background” and the rest of the layers. You can use it as the background for the “Lines” option.
22 - Or you can hide together with the “Colors” layer it and use the “Greys option. This choice is better if the image you chose is complex and it may be tedious to add the numbers to the outlined portions.
23 - In less complicated images, you can add the numbers to the outlined portions and use that option instead. Check it out!