GIMP Graphic Image Manipulation Program

GIMP Image manipulation software Free Open Source Written by two students First version in 1996

GIMP User interface Dialogs Image type Color mode Layers Channels Alpha channel The selection Quick Mask Undoing Grids and Guides Brushes Paths Patterns Text and fonts Palettes Script-Fu Tools Filters

You are stuck. What to do? There is a floating selection. The selection is hidden. You are acting outside the selection. Other layer is active. You are acting outside the layer.

Floating selection Temporary layer If there is a floating selection, many actions are impossible. What can you do with floating selection? –Anchor –Create a new layer

Paths One dimensional curve Path dialog Can be saved Path can be converted into selection Selection can be converted into path –Information might be lost Paths are defined by anchors and handles –Each anchor point has two handles Text can be converted into path

File formats GIMP's native XCF format Every other format preserves some image properties and loses others Other formats –Tif, jpg, bmp –Gif (transparent background, animated) –Psd (Photoshop)

Mode RGB –Three color channel (Red, green blue) –No color gives black –Used for monitor display Grayscale –One color and one alpha channel Indexed image CMYK –Cyan, magenta, yellow, black –No color gives white –Use for press

Channel Color channels: –Red, Green, Blue Alpha (transparency value) Selection masks Channel can be used to save the selection.

Selection When you operate on an image, you only want part of it to be affected Selection is represented by marching ants Selection is actually a grayscale channel By default the mask is shown in red Pixel values ranging from 0 (unselected) to 256 (fully selected) You can use any of the paint tools, as well as the bucket fill and gradient fill tools, in this way

Quick mask Selection tools have limits Quick Mask shows the full structure of selection With QM you can paint the selection

Layer Layers dialog Layer is a page in a book Only one layer is active Transparency You can change the size of the lazer Visibility Linkage to other layers

Undoing Almost anything you do to an image in GIMP can be undone More convenient to work with the Undo History dialogUndo History dialog GIMP allocates a certain amount of memory to each image for undoing

Grids and guides

Brushes

Tools Selection Brush

Tool box options

Selection Tools Rectangle Select Ellipse Select Free Select (the Lasso) Select Contiguous Regions (the Magic Wand) Select by Color Select Shapes from Image (Intelligent Scissors)

The Rectangle Selection tool is designed to select rectangular regions of an image The Ellipse Selection tool is designed to select circular and elliptical regions from an image The Free Selection tool, or Lasso, lets you create a selection by drawing it free-hand with the pointer The Fuzzy Select (Magic Wand) tool is designed to select areas of the current layer or image based on color similarity, selecting contiguous pixels whose colors are similar to the starting pixel The Select by Color tool is designed to select areas of an image based on color similarity, selects all pixels that are sufficiently similar in color to the pixel you click on, regardless of where they are located The Intelligent Scissors tool is an interesting piece of equipment: it has some features in common with the Lasso, It is useful when you are trying to select a region defined by strong color-changes at the edges

Selection modes Replace mode will cause any existing selection to be destroyed or replaced when the new selection is created. Add mode will cause the new selection to be added to any existing selection regions. Subtract mode will remove the new selection area from any existing selection regions. Intersection mode will make a new selection from the area where the existing selection region and the new selection region overlap.

Brush Tools

Options

The Dodge or Burn tool uses the current brush to lighten or darken the colors in your image The Convolve tool uses the current brush to locally blur or sharpen your image The Smudge tool uses the current brush to smudge colors on the active layer or a selection. It takes color in passing and uses it to mix it to the next colors it meets, on a distance you can set

Transform Tools Move Tool Crop Tool Rotate Tool Scale Tool Shear Tool Perspective Tool Flip Tool

Other tools Path Tool Bucket Fill Gradient Tool Color Picker Tool Magnify Tool Measure Tool Texttool

Color Tools Color Balance Tool Hue-Saturation Tool Colorize Tool Brightness-Contrast tool Threshold Tool Levels tool Curves Tool Posterize Tool

Color Balance Tool The color balance tool modifies the color balance of the active selection or layer.

Hue-Saturation Tool The Hue-Saturation tool is used to adjust hue, saturation and lightness levels on a range of color weights for the selected area or active layer.

Colorize Tool The Colorize tool renders the active layer or selection into a greyscale image seen through a colored glass.

Brightness-Contrast tool The Brightness-Contrast tool adjusts the brightness and contrast levels for the active layer or selection. Levels and Curve tools are more efficient.