The document provides a tutorial on using the G'MIC water color filter to create watercolor effects in both G'MIC and GIMP. It explains how the G'MIC filter works by creating cyan, magenta, and yellow channels and mixing them. It then provides step-by-step instructions for recreating a similar effect in GIMP, including reducing detail, enhancing edges, moving to CMY color space, creating color layers, adding line art, and painting with watercolor brushes. The tutorial is intended to help new users learn how to produce results with the G'MIC filter and create watercolor styles in GIMP.
1. G'MIC Water color filter
tutorial on using the filter and
how similar effect can be created using Gimp
G'MIC filter programming: Tom Keil
Tutorial: Arto Huotari
2. Section 1: G'MIC Water color filter
G'MIC water color filter creates channels of Cyan, Magenta and
Yellow and mixes them to each other for different colors. Water
color like effect is created by preliminary preparation of the image
and textured masks created with Cubism and Fuzzy frame filters.
For deeper understanding it is recommended to read through the
second section of the tutorial.
Whole range of the effect is presented in video
“Travel in water color” by Zonder.
3. G'Mic Water color filter, learning the filter
Since the filter has a lot of settings it may be that for your image the filter does not produce
desired results with the default settings. This tutorial aims to help new user to produce some
result and hopefully lead to quicker learning of the filter.
Start by setting all sliders to left except Cyan Stroke Strength, Magenta Stroke Strength and
Yellow Stroke Strength. Set these sliders to the right. Preview should now look black. Next
slide color intensity slider to the right to get colors to the preview window
4. G'Mic Water color filter, learning the filter
Next go to the Color brushes settings section and slide the edge distance sliders. Start with
the strongest color and proceed to weaker colors next. Move the sliders so that you have
three stacked boxes of different size.
5. G'Mic Water color filter, learning the filter
Next set the abstraction setting to your liking. Again start with the strongest color
6. G'Mic Water color filter, learning the filter
Next increase the brush size to merge the grains of individual colors
7. G'Mic Water color filter, learning the filter
To complete the color settings move the stroke strength sliders to left in order to smooth out
and weaken the colors.
8. G'Mic Water color filter, learning the filter
Set paper color, texture and invert colors settings. Then revert back to the top of the dialogue
and adjust Light colors slider at least to 0.01. Note that the effect of the slider may not be
linear. Note the difference between 0.05 and 0.06. This is caused by high color intensity and
zero dark colors setting. Adjust color intensity settings and click OK to process the image
9. G'Mic Water color filter, learning the filter
Final image processed with the previous values
10. Section 2: Creating the effect in Gimp.
Base image used in this tutorial is 1164x947 pixels. For larger images effect
produces different results and different values for parameters should be used.
11. Step 1: Reduce the detail of the image using selective Gaussian blur
Duplicate background layer, select Filters → Blur → Selective Gaussian blur
Slice of unmodified image is shown on the right. Blur was done using with radius
10 and delta 30
12. Step 2-1: Enhancing and bringing out the remaining detail. Duplicate the layer.
Filters → Edge detect → Edge → Sobel (with value 3 in this case)
Edit → Fade Edge→ Dodge (middle slice)
Set layer mode to Value (right slice)
13. Step 2-2: Enhancing and bringing out the remaining detail. Duplicate the layer,
Set layer mode to burn
Filters → Blur → Gaussian blur (value 5)
Filters → Edge Detect → Edge → Sobel (3)
Edit → Fade Edge → Divide
Right click to layer → Add layer mask → Gray scale copy → Invert colors → Add
Previous Burn Blur Sobel Masked
Divide
14. Step 2-3: Enhancing and bringing out the remaining detail. Duplicate the third
layer in the stack. Move it to top, set layer mode to Devide
Filters → Blur → Gaussian blur (value 10)
Filters → Edge Detect → Edge → Sobel (6)
Edit → Fade Edge → Divide
Right click to layer → Add layer mask → Gray scale copy → Invert colors → Add
From
step 2-2 Step 2-3 final
15. Step 2-3: Explained
Both blur value and edge detection intensity were increased from previous step. If
we look in to the images with out masks a difference can be seen.
Image on the left has smaller blur value and edge detection intensity. There are
more detail edges present and the edges are thinner.
16. Step 2-3: Explained
On step 2-3 layer mode divide was used instead of burn. By zooming in to the
image and changing layer modes the difference can be seen.
Different layer modes give different results. Idea here is not to use only burn
since using burn only creates very dark and strong edges. Our target is to create
water color like image we want to enhance the edges with out making them too
dark and sharp
Before Divide
Dodge
Burn
Value
17. Step 2-4: Continue duplicating the third layer on the stack and use increasing blur
and Edge Detect values until the layer bitmap is white after divide. Disregard the
white layer. With the example image, blur value 40 loses all detail.
There are multiple ways to vary the layer stack. Layer mode of each layer affects the end
result, also different result is produced if the visible result (edit copy visible) of previous
step is used instead of third layer in the stack for each new enhancement layer (paste as
new layer). Now is a good time to save the image and also save it to different name and
continue with new copy.
18. Step 3-1: Spread strong colors
Blank the background layer. Select one of the visible layers, right click and select
“merge visible layers.”
19. Step 3-1: Spread strong colors
Duplicate the layer
Break the image to LAB channels.
Colors → Components → Decompose → LAB
Blank A and B layers and select L layer.
From tool box select tool “select by color”
Zoom in to the image and select as dark pixel you can find and set the selection
threshold to your liking. For sample image the L channel was very light so I used
threshold of 30. Idea here is to simulate the spread of strong water color because
of absorption to paper.
21. Step 3-3: Spread strong colors, recompose the image.
Select → None
Unblank the A and B layer
Colors → Components → Recompose. Note that this will compose the image to
the layer it was originally decomposed from. It is recommended to rename the
layer now to “From LAB”
Original
Modified
22. Step 4-1: Move to CMY color space / preparation
Duplicate the “From LAB” layer
Invert colors of the “From LAB” layer
Add new layer with a black color
Add new layer with a white color
Blank the black and white layer
Activate the “Inverted From LAB” layer.
23. Step 4-2: Move to CMY color space ... / create color layers
Switch to the channels tab and blank Green and Blue channels
Edit → Copy Visible
Edit → Paste as new layer
Move the layer on top of black layer
Rename the layer as Cyan
Blank the layer
Select “Inverted From LAB” layer
24. Step 4-3: Move to CMY color space / create color layers
Repeat previous steps for green and blue channel
Switch to channels tab and blank Red and Blue channels
Edit → Copy Visible
Edit → Paste as new layer
Move the layer on top of black layer
Rename the layer as Magenta
Blank the layer
Select “Inverted From LAB” layer
Switch to the channels tab and blank Red and Green channels
Edit → Copy Visible
Edit → Paste as new layer
Move the layer on top of black layer
Rename the layer as Yellow
Blank the layer
Switch to channels tab and turn on all channels
Switch back to layers tab and add black mask to Cyan,
Magenta and Yellow layers
Final layer stack is shown on the right
25. Step 4-4: Move to CMY color space / set layer modes
Unblank the layers and set layer modes as shown
Your image should be completely white now
Difference
Addition
Addition
Addition
Normal
26. Step 5-1: Create line art
Use your favorite method of creating the line art and place it on top of layer
stack. Use the original image to create the line art.
This was created by
Filters → Blur → Selective Gaussian Blur 3 with delta 15
Filters → G'Mic → Artistic → B&W Pencil with default values
Colors → Levels to lighten the sketch if necessary
Set layer mode to Multiply
27. Step 6-1: Use water color brushes to paint out the colors. Use white color to paint
on the black masks of the Cyan, Magenta and Yellow layers.
Final image and final layer stack shown.
Note that also red, green and blue can be added to color layers as has been
done here to bring to make the water look blue instead of brown.
28. End of tutorial
Thank you
And also thank you for following persons and services for water color
brushes that were used to create image on second
Section of the tutorial.
http://www.brusheezy.com/members/jermshaw
http://www.brusheezy.com/members/Aqs
http://mcbadshoes.deviantart.com/
http://www.env1ro.deviantart.com