- The Book of GIMP: A Complete Guide to Nearly Everything
- Introduction
- I. Learning GIMP
- 1. Getting Started
- 2. Photograph Retouching
- 2.1 Tutorial: Enhancing Badly Taken Photographs
- 2.2 Global Transformations
- 2.3 Local Transformations
- 2.4 Retouching a Scanned Photograph
- 2.5 Advanced Techniques
- 2.6 Exercises
- 3. Drawing and Illustration
- 3.4 Dodging, Burning, and Smudging
- 3.5 The Digital Painting Process
- 3.6 Drawing Shapes
- 3.7 Exercises
- 4. Logos and Textures
- 5. Composite Photography
- 6. Animation
- 7.1 Tutorial: Extracting Information from a Picture
- 7.2 The Principles of Preprocessing
- 7.3 Filtering
- 7.4 Edge Detection
- 8. Designing a Website
- 8.5 Exercises
- II. Reference
- 9. The GIMP Interface
- 10. Display
- 11. Layers
- 12. Color
- 13. Selections
- 14. Masks
- 15. Drawing Tools
- 16. Transformation Tools
- 17. Filters
- 17.1 Common Properties
- 17.2 The Blur Filters
- 17.3 The Enhance Filters
- 17.4 The Distorts Filters
- 17.5 The Light and Shadow Filters
- 17.6 The Noise Filters
- 17.7 The Edge-Detect Filters
- 17.8 The Generic Filters
- 17.9 The Combine Filters
- 17.10 The Artistic Filters
- 17.11 The Decor Filters
- 17.12 The Map Filters
- 17.13 The Render Filters
- 18. Animation Tools
- 19. Obtaining and Printing Images
- 20. Image Formats
- 21. Scripts and Plug-ins
- 22. Customizing GIMP
- III. Appendices
- A. Vision and Image Representation
- B. Tips and Hints for Selected Exercises
- C. Resources
- D. Frequently Asked Questions
- D.1 What Does the Future Hold?
- D.2 How...?
- How can I draw a straight line?
- How can I draw a circle?
- How can I create an outline around text?
- How do I save a selection within an image to a file?
- How do I merge an image from another file with the current image?
- How do I get small fonts to look as nice as large fonts?
- How do I set keyboard shortcuts?
- How do I set up GIMP so a layer becomes active when I click an element in that layer?
- How do I fill a layer or selection with transparency?
- How do I draw in a different color?
- How do I add a blur to my image?
- How can I paint along the outline of a rectangle?
- How do I move existing guides?
- How do I get rid of a floating selection?
- How do I paint in a transparent area?
- How can I see the marching ants and know whether my selection has been made?
- How can I add color to a black and white image?
- How do I resize my photo to a precise size, say 5 × 7 cm?
- How do I set the foreground color to a color in my image?
- How can I keep text sharp when scaling it down?
- How do I copy a layer mask to another layer mask?
- How can I search for a specific font, brush, or pattern?
- How do I erase with a tool other than the Eraser?
- How can I use the Scale tool to enlarge an image?
- How can I find a dialog I closed by accident?
- How can I invert grayscale values without changing the colors?
- How do I crop with a defined aspect ratio?
- D.3 Why...?
- Why are some of the filter names grayed out?
- Why is nothing happening?
- Why doesn’t anything happen when I try to cut, paste, or apply a filter to a selection?
- Why can’t I modify the channel I built by saving a selection?
- Why can’t I change my image after I saved a selection to a channel?
- Why do my paint strokes appear on the image when I try painting on a layer mask?
- Why did the size of my file increase when I exported it to JPEG with 100% quality?
- Why can’t I draw in the color I chose?
- E. Installing GIMP
- F. Batch Processing
- Index
- About the Authors
- Copyright
The filters in the Combine menu are used to combine two or more images. We omit Film-strip, since film is rarely used nowadays.
Depth Merge merges two images using two image maps as guides. It requires four images in total, and they must all be the same size. An image map must be grayscale. The dark areas correspond to areas that will be visible in the associated image, and light areas of the map will be transparent areas in the associated image. In other words, the map acts as a mask.
The images shown in Figure 17-139 and Figure 17-140 were used to demonstrate the filter. First they were cut and scaled until they were the same size. To build the maps shown in Figure 17-141 and Figure 17-142, we did the following:
Chose the Select by Color tool.
Clicked a light area of the image, pressed and held
, and then clicked other light areas until all of the light areas in the image were selected.Created a new white layer.
Inverted the selection and filled it with black.
Dragged the new layer to the Toolbox to create a new image with it.
Deleted the mask layer from the image.
When the Depth Merge filter is selected, the dialog shown in Figure 17-143 pops up. The menus on the right are used to set the source and depth image maps. The remaining parameters are as follows:
OVERLAP [0 to 2] smooths the transition between images using semitransparency.
OFFSET [–1 to +1] adjusts the respective visibility of the Source images in the resulting image.
SCALE [–1 to +1] does the same thing as OFFSET, but separately for each image, by darkening its map when the value of Scale is lowered.
See the result in Figure 17-144.
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