I tried writing this tutorial in GIMP again, but it was too long. :P So I uploaded copies of my steps, which hopefully will be helpful!
From
this to
IN 14 STEPS
Involves Color Balances
Many of the settings in this tut can be adjusted to work with your image. I'll put a ♥ next to the adjustable settings. :D
Step 1 - Get your base image. Crop, resize (Tools>Transform Tools>Crop & Resize), & sharpen (Filters>Enhance>Sharpen). (Mine was set to 10)
Step 2 - Duplicate the base image. Go to Gaussian Blur (Filters>Blur>Gaussian Blur), with the Blur Radius set to 0.6. Set this layer to Screen, opacity 40. ♥
Step 3 - Duplicate the base image, drag to the top, & set to Soft Light, opacity 40. ♥
Step 4 - Copy the image (Edit>Copy Visible), & then paste (Edit>Paste). Rename this new layer Base 2.
Step 5 - Add a new layer (Layer>New Layer), & fill it with the color #95c29c. (a light green)
Set the layer to Addition, opacity 5.
Step 6 - Duplicate Base 2, drag it to the top, & set to Saturation, opacity 100.
Step 7 - Repeat Step 3, only this time rename the new layer Base 3.
Step 8 - Duplicate Base 3. Open up Color Balance (Layer>Colors>Color Balance), & put in these settings:
Shadows: 0, -10, 0
Midtones: -20, 10, 5
Highlights: -10, 2, 5
The settings vary based on your image, though you want a blue-ish/green-ish tone to your image
Step 9 - Duplicate Base 3, drag to the top, & set to Soft Light, opacity 50. ♥
Step 10 - Repeat step 3, renaming the new layer Base 4.
Step 11 - Duplicate Base 4, setting to Addition, opacity 10.
Step 12 - Add a new layer, filling it with color #011928. (A dark blue)
Step 13 - Duplicate the color layer twice. Set the 1st & 3rd layer to Screen, opacity 100. Set the 2nd layer to Subtract, opacity 100.
Step 14 - Duplicate Base 2 & drag it to the top. Set the layer to Soft Light, opacity 20. ♥
& that's it!
I hope this tutorial helped! Let me know if you have any questions, & I'll try to help you out. :)
I love seeing you results! ;D
Other icons made with this tutorial: