This tutorial is all about making selections and colorizing parts of your digital artwork. you can use the techniques here to colorize anything. Or make the rainbow as shown and use it as a background, or a fill for type.
I'll demonstrate with Photoshop, but you can use any decent image editing program.
Step 1: The Base
I started with this cool blue glitter jpeg from Creative Market. This will make my rainbow glittery, even when I change the colors. You can choose any color from the glitter textures download as your base. Here's the link:
Step 2: The First Color
You won't be adding anything to the base, just changing the colors in sections. I drew my selections by hand for a illustrated look. You can use the brushes, like I did, or make smooth selections with the vector graphics tools. I think hand drawing for this kind of project is more fun. Just wish I had a Wacom tablet.
To start your rainbow:
1) Select quick maskmode.
2) Choose a brush and freehand draw the shape you want for your first color. The lower the opacity setting for the brush, the more the texture will show, but the less color change you'll have. I set the opacity to about 60% - 80%. The pink arch is my mask, it is not the color of my artwork.
3) Save your selection (the mask you just drew), as shown, and name it. This arch is the middle of my rainbow and will be yellow.
Step 3: Colorize
4) Load your selection (it looks like shiny, wiggly lines). Make sure the arch is the part selected. If not, invert your selection. If you want to hide your selection, but still use it, hit command-H.
5) Go to image-adjustments-hue/saturation.
6) Click colorize and preview in the dialog box.
7) Now use the sliders to change the color inside your selection. (If your selection is hidden, it looks like magic.)
I needed yellow for the center of my rainbow, so I slid the hue to yellow. It was too muddy so I increased the saturation. The yellow was too dark so I increased the lightness.
8) When you have the color you want, deselect your selection. (Remember, it's saved in case you want to change something later.)
That's it. That's how to select and colorize a piece of any image. The rest of the rainbow will be created using these same steps for each color until the fine-tuning at the end.
Step 4: Orange
Draw a new mask (pink) where you want the next color band to go. Load and save this as a new selection like in the previous steps. I saved mine as "orange".
Masks can be erased with the eraser just like any other drawing. Set the background color to white.
Step 5: Colorize
Using image-adjustments-hue/saturation, I turned the new selection orange. Note how I used different settings for the new color.
Step 6: Red
Use the same process for the red band.
Step 7: The Rest of the Rainbow
Keep going until you have all the colors of the rainbow.
Step 8: Fine Tune
I used the dodge tool and brightness/contrast to lighten up the image without losing any detail or color.
Step 9: Extras
I added a lens flare from filters-render-lens flare. Just for fun.
I hope this instructable is helpful in your digital art projects. If you enjoyed it and find it useful, please remember to vote.
Also, I love to see what people make with my instructables, so please click the I made it button and show what you've done. Thanks!
And have fun!