際際滷

際際滷Share a Scribd company logo

GIMP Tutorial.pptx

Download as PPTX, PDF
Bruno Pereira
Bruno Pereira

1. GIMP (GNU Image Manipulation Program) is an open source, cross-platform bitmap graphics editor that can be used to edit and manipulate images. 2. Basic tools in GIMP allow the user to straighten, crop, adjust brightness and contrast, use color levels and alpha channels, perform pseudo-color overlays, scale images, and export files in different formats like PNG. 3. When editing images for scientific purposes, it is important to only use tools in an ethical manner and avoid overly adjusting brightness, contrast, or colors in a way that misrepresents the original data.

1 of 29
Download to read offline
GIMP Tutorial v2018-11 Boo Virk, Simon Andrews, Jo Montgomery Babraham.bioinformatics@babraham.ac.uk
What is GIMP GNU Image Manipulation Program Bitmap Graphics Editor Open Source Cross Platform Not for Vector editing www.gimp.org
Vector vs Bitmap
Getting GIMP Open Source Cross Platform www.gimp.org
View Toolbox Windows > New toolbox or (Ctrl + B) View Layers Dialogue box Windows > Dockable Dialogs > Layers or (Ctrl + L) GIMP can do a lot of things will show you small selection of tools that are ethically acceptable to use for figure production Basic Layout
Opening Images To open an image for editing: Drag file onto a new GIMP window or File > Open or (Ctrl + O) After opening, save a working copy of the file GIMP saves files as XCF files by default, but you can export files in other formats (e.g. PNG)
Straightening Images Drag a horizontal guide line onto your image (from top ruler) to intersect an area that should be perfectly horizontal Using the Rotate tool (Shift + R) rotate the image so that it lines up with the guideline When you start to rotate the image, a dialogue box will appear
Straightening Images When finished click the rotate button to apply To remove guideline: Image > Guides > Remove all Guides
Cropping Images Useful to crop unnecessary edges away Can reduce file size when bringing images into a vector file Use the Rectangle Select tool (R) to draw a box around the area of the image you want to keep
Click and drag the corners of the box after drawing to fine tune Crop: Image > Crop to Selection Cropping Images Dont forget about Ethics!
Brightness and Contrast Increasing Brightness Increasing Contrast
Brightness and Contrast Adjusting brightness and contrast can help the clarity of your image In GIMP, Colours > Brightness-Contrast If a selection box is marked, brightness and contrast will be adjusted in selected area only
Brightness and Contrast Original Brightness and Contrast adjusted Brightness and Contrast adjusted too much image is oversaturated Unethical
Colour Levels Brightness and contrast should be edited by adjusting colour levels Colors > Levels Or: Dialogue box shows histogram of colour value usage Useful to display a Logarithmic histogram so that values arent hidden at the bottom of the graph
Colour Levels Display Logarithmic Histogram The middle handle will adjust the midpoint of the levels and represents non-linear editing of colours. This is not ethically acceptable for publication!
Alpha channel Alpha channels are masks through which you can display images Within an alpha channel: White acts as the visible area Black acts as the transparent area Level of gray in between determines the level of visibility.
Why use an alpha channel? 0 50 100 150 200 250 0 50 100 150 200 250
In GIMP Layer > Transparency > Add Alpha Channel
Colour to Alpha Channel You can assign a colour to the alpha channel, which will make all pixels in your image with the assigned colour transparent In GIMP Colors > Color to Alpha Use this tool to pan around the preview Preview, indicating which areas are to be transparent Colour swatch for selecting colour to become transparent
Pseudo-colour Overlays Some experiments such as FISH microscopy may generate multiple greyscale images which can be overlaid to form a pseudo-colour image
Ensure image is in RGB mode Image > Mode > RGB Assign a single colour to each image (v2.8) Color > Colorify Pseudo-colour Overlays
Ensure image is in RGB mode Image > Mode > RGB Assign a single colour to each image (v2.10) Help > Search and Run a command Colorify Colorify Replace all colors with shades of a specified color Pseudo-colour Overlays
Or Colors > Levels Dial down the colours you dont want
Once images are correct colours, we need to overlay them Open Layers dialogue box (if not already open) Windows > Dockable Dialogues > Layers (Ctrl+L) Pseudo-colour Overlays
Click and drag image layer in to the working window of another image Repeat this until one image has all of the desired layers
Finally, make each layer (except the bottom layer) show only its colour, making the underlying layers visible Layer Dialogue Box -> Mode > Lighten Only
21/01/2024 Creating Scientific Figures
Scaling Images GIMP can be used to scale the size of your image Image > Scale Image Avoid making your images bigger than original size, bitmaps do not scale up well!
Exporting Images Once editing is done, and the working XCF file is saved, you need to export the image File > Export As Specify file format e.g. PNG Always save your image as a PNG file, maintains transparency (alpha channel) and is lossless

More Related Content

GIMP Tutorial.pptx

  • 1. GIMP Tutorial v2018-11 Boo Virk, Simon Andrews, Jo Montgomery Babraham.bioinformatics@babraham.ac.uk
  • 2. What is GIMP GNU Image Manipulation Program Bitmap Graphics Editor Open Source Cross Platform Not for Vector editing www.gimp.org
  • 4. Getting GIMP Open Source Cross Platform www.gimp.org
  • 5. View Toolbox Windows > New toolbox or (Ctrl + B) View Layers Dialogue box Windows > Dockable Dialogs > Layers or (Ctrl + L) GIMP can do a lot of things will show you small selection of tools that are ethically acceptable to use for figure production Basic Layout
  • 6. Opening Images To open an image for editing: Drag file onto a new GIMP window or File > Open or (Ctrl + O) After opening, save a working copy of the file GIMP saves files as XCF files by default, but you can export files in other formats (e.g. PNG)
  • 7. Straightening Images Drag a horizontal guide line onto your image (from top ruler) to intersect an area that should be perfectly horizontal Using the Rotate tool (Shift + R) rotate the image so that it lines up with the guideline When you start to rotate the image, a dialogue box will appear
  • 8. Straightening Images When finished click the rotate button to apply To remove guideline: Image > Guides > Remove all Guides
  • 9. Cropping Images Useful to crop unnecessary edges away Can reduce file size when bringing images into a vector file Use the Rectangle Select tool (R) to draw a box around the area of the image you want to keep
  • 10. Click and drag the corners of the box after drawing to fine tune Crop: Image > Crop to Selection Cropping Images Dont forget about Ethics!
  • 11. Brightness and Contrast Increasing Brightness Increasing Contrast
  • 12. Brightness and Contrast Adjusting brightness and contrast can help the clarity of your image In GIMP, Colours > Brightness-Contrast If a selection box is marked, brightness and contrast will be adjusted in selected area only
  • 13. Brightness and Contrast Original Brightness and Contrast adjusted Brightness and Contrast adjusted too much image is oversaturated Unethical
  • 14. Colour Levels Brightness and contrast should be edited by adjusting colour levels Colors > Levels Or: Dialogue box shows histogram of colour value usage Useful to display a Logarithmic histogram so that values arent hidden at the bottom of the graph
  • 15. Colour Levels Display Logarithmic Histogram The middle handle will adjust the midpoint of the levels and represents non-linear editing of colours. This is not ethically acceptable for publication!
  • 16. Alpha channel Alpha channels are masks through which you can display images Within an alpha channel: White acts as the visible area Black acts as the transparent area Level of gray in between determines the level of visibility.
  • 17. Why use an alpha channel? 0 50 100 150 200 250 0 50 100 150 200 250
  • 18. In GIMP Layer > Transparency > Add Alpha Channel
  • 19. Colour to Alpha Channel You can assign a colour to the alpha channel, which will make all pixels in your image with the assigned colour transparent In GIMP Colors > Color to Alpha Use this tool to pan around the preview Preview, indicating which areas are to be transparent Colour swatch for selecting colour to become transparent
  • 20. Pseudo-colour Overlays Some experiments such as FISH microscopy may generate multiple greyscale images which can be overlaid to form a pseudo-colour image
  • 21. Ensure image is in RGB mode Image > Mode > RGB Assign a single colour to each image (v2.8) Color > Colorify Pseudo-colour Overlays
  • 22. Ensure image is in RGB mode Image > Mode > RGB Assign a single colour to each image (v2.10) Help > Search and Run a command Colorify Colorify Replace all colors with shades of a specified color Pseudo-colour Overlays
  • 23. Or Colors > Levels Dial down the colours you dont want
  • 24. Once images are correct colours, we need to overlay them Open Layers dialogue box (if not already open) Windows > Dockable Dialogues > Layers (Ctrl+L) Pseudo-colour Overlays
  • 25. Click and drag image layer in to the working window of another image Repeat this until one image has all of the desired layers
  • 26. Finally, make each layer (except the bottom layer) show only its colour, making the underlying layers visible Layer Dialogue Box -> Mode > Lighten Only
  • 28. Scaling Images GIMP can be used to scale the size of your image Image > Scale Image Avoid making your images bigger than original size, bitmaps do not scale up well!
  • 29. Exporting Images Once editing is done, and the working XCF file is saved, you need to export the image File > Export As Specify file format e.g. PNG Always save your image as a PNG file, maintains transparency (alpha channel) and is lossless

Editor's Notes

  1. Version 2.8 still works like this. They have removed this function from newer versions. For version 2.10, see next slide.
  2. V 2.10 you can either add a plug-in (code) or just follow these simple steps