M8. Introduction to GIMP

1. M8. Introduction to GIMP

2. Introduction: • GIMP is an acronym for GNU (pronounced “guh-noo”) Image Manipulation. The GIMP is a multiplatform tool suitable for a variety of image manipulation tasks, including photo retouching, image composition and image construction. • The first version of the GIMP were written by Peter Mattis and Spencer Kimball. • Wilber is the official mascot of the GIMP.

3. MAIN WINDOWS LAYERS DIALOG IMAGE WINDOW MAIN TOOLBOX TOOL OPTIONS BRUSHES/PATTERNS/GRADIENTS

4. The Main Toolbox: It is the heart of GIMP. This toolbox contains the highest level menu, and a set of icon buttons that can be used to manipulate image. Tool options: It is located below the main Toolbox and it shows options for the currently selected tool. An image window: Every image open in GIMP is displayed in a separate windows. Layers Dialog: This dialog window shows the layer structure of the currently active image, and allows it to be manipulated in a variety of ways. . Brushes/Patterns/Gradients: The layer dialog shows the dialogs for managing brushes, patterns and gradients.

5. MAIN TOOLBOX TOOLBOX MENU TOOL OPTIONS FOREGROUND/BACKGROUND BRUSH/PATTERN/GRADIENT ACTIVE IMAGE

6. Toolbox Menu: It contains some commands that cannot be found in the menus that are attached to images. These include commands for setting preferences, creating certain types of dialogs, etc. Tool icons: These icons are buttons which activate tools for a wide variety of purposes: selecting parts of images, painting on them, transforming them, etc. Foreground/Background colors: The color areas here show you GIMP's current foreground and background colors, which come into play in many operations.

7. Brush/Pattern/Gradient:The symbols here show you GIMP's current selections for: the Paintbrush, used by all tools that allow you to paint on the image; for the Pattern, which is used in filling selected areas of an image; and for the Gradient, which comes into play whenever an operation requires a smoothly varying range of colors. Active Image: In GIMP, you can work with many images at once, but at any given moment, one of them is the “active image”.

8. IMAGE WINDOWS TITLE BAR IMAGE WINDOW RESIZE TOOGLE IMAGE MENU MENU BUTTON RULER INACTIVE PADDING AREA IMAGE DISPLAY QUICK MASK TOGGLE NAVIGATION CONTROL POINTER COORDINATES ZOOM BUTTON STATUS AREA UNITS MENU CANCEL BUTTON

9. Title Bar: This bar show the name of the image and some basic information about it. Image Menu: Directly below the emphasis bar appears the Image Menu. This menu gives you access to nearly every operation you can perform on an image. Menu Button: Clicking on this little button gives you the Image Menu, except in a column instead of a row. Ruler: In the default layout, rulers are shown above and to the left of the image, indicating coordinates within the image.

10. QuickMask Toggle: At the lower left corner of the image display is a small button that toggles on or off the Quick Mask, which is an alternate, and often extremely useful, way of viewing the selected area within the image. Pointer Coordinates: In the lower left corner of the window is a rectangular area used to show the current pointer coordinates, whenever the pointer is within the image boundaries. The units are the same as for the rulers. Units menu: By default, the units used for the rulers and several other purposes are pixels.

11. Zoom button: There are a number of ways to zoom the image in or out, but this menu is perhaps the simplest. Status Area: The Status Area appears below the image display. Most of the time, by default, it shows which part of the image is currently using. Cancel Button: This is used to cancel operations (example: complex and time consuming) Navigation control: This is a small cross-shaped button at the lower right corner of the image display. Clicking on it, and holding the left mouse button down, brings up a window showing a miniature view of the image, with the displayed area outlined.

12. Inactive Padding Area: This padding area separates the active image display and the inactive padding area, so you're able to distinguish between them. Image Display: The most important part of the image window. It occupies the central area of the window, it is surrounded by a yellow dotted line to show the image boundary, against a neutral gray background. 14. Image Window Resize Toggle: If this button is pressed, the image itself will be resized if the image window is resized.

13. Overview • Opening GIMP • Default GIMP Layout • Layers • Duplicating Layers • Adding Color to Layers • Layer Order • Opacity • Selection Tools • Selection Tools Descriptions

14. 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)

15. 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

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

17. 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

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

19. 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

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

21. Grids and guides

22. Opening GIMP • There should be a GIMP icon on your desktop • You can also open GIMP through the Start Menu (Start  All Programs  GIMP 2)

23. Default GIMP Layout • When GIMP opens, the default setting is three different dialogues (windows) • Toolbox • Active Image • Layers

24. Layers • Creating Layers • In the Active Image Dialogue go to File  New. • This will open a dialogue box with options on the size of an image you would like to create. For this tutorial, enter the width as 200 and the height as 200 and click the Okay button. • An untitled dialogue window should open with the image sized at 200x200.

25. Duplicating Layers If you look at the Layers Dialogue, you should see that this new image is called “Background”. In the Layers Dialogue, click on the Duplicate Layer button. In the Layers Dialogue you should see a new layer named “Background Copy.”

26. Adding Colors to Layers • Highlight the Background copy layer selected (highlighted) in the Layers Dialogue. • Go to the GIMP Toolbox and double click on the Foreground Color button, which will open the Change Foreground Color tool. • In the HTML notation box type in FF0000 (this is the hexidecimal code for red) and then click OK.

27. Adding Colors to Layers (cont.) • In the Active Image Dialogue go to Edit Fill with FG Color. • This will fill the Background copy layer with red. • In the Layers Dialogue click on the Background layer to select it. • Repeat the same steps on the Background layer, making this layer blue (hexidecimal code 0000FF).

28. Layer Order • When you look at the Layers Dialogue you can see the red and blue layers. The red layer is at the top of the stack, so that is the one that shows up in the image. • With the blue layer selected in the Layers Dialogue, click the UP arrow and. You will now see that the blue layer is at the top of the stack and the image is now blue. • Of course, this works vice-versa, and you can move the blue layer down by selecting it in the Layers Dialogue and then clicking the DOWN arrow.

29. Opacity • What do you get when you mix red and blue? Purple, of course! • Select the top layer from the Layers Dialogue (doesn’t matter which layer is on top). • Adjust the opacity in the Layers Dialogue until it is at 50%. • The image in your Active Dialogue should now be purple.

30. Selection Tools • There are several selection tools available in GIMP: • Rectangle Select Tool • Ellipse Select Tool • Free Select Tool • Fuzzy Select Tool • Select by Color Tool • Scissors Select Tool • Foreground Select Tool

31. Selection Tools Descriptions • The Rectangle Selection tool is designed to select rectangular regions of the active layer: it is the most basic of the selection tools, but very commonly used. • The Ellipse Selection tool is designed to select circular and elliptical regions from an image, with high-quality anti-aliasing if you want it. • The Free Selection tool, or Lasso, lets you create a selection by drawing it free-hand with the pointer, while holding down the left mouse button (or, for a stylus, pressing it against the tablet). When you release the mouse button, the selection is closed by connecting the current pointer location to the start location with a straight line. You can go outside the edge of the image display and come back in if you want to. The Lasso is often a good tool to use for “roughing in” a selection; it is not so good for precise definition. • The Fuzzy Select (Magic Wand) tool is designed to select areas of the current layer or image based on color similarity. When using this tool, it is very important to pick the right starting point. If you select the wrong spot, you might get something very different from what you want, or even the opposite. The Wand is a good tool for selecting objects with sharp edges. It is fun to use, so beginners often start out using it a lot. You will probably find, however, that the more you use it, the more frustrated you become with the difficulty of selecting exactly what you want, no more, no less.

32. Selection Tools Descriptions (cont.) • The Select by Color tool is designed to select areas of an image based on color similarity. It works a lot like the Fuzzy Select tool (“Magic Wand”). The main difference between them is that the Magic Wand selects contiguous regions, with all parts connected to the starting point by paths containing no large gaps; while the Select by Color tool 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, some features in common with the Path tool, and some features all its own. It is useful when you are trying to select a region defined by strong color-changes at the edges. To use the Scissors, you click to create a set of "control nodes", also referred to as anchors or control points, at the edges of the region you are trying to select. The tool produces a continuous curve passing through these control nodes, following any high-contrast edges it can find. If you are lucky, the path that the tool finds will correspond to the contour you are trying to select. • This tool lets you extract the foreground from the active layer or from a selection. It is based on the SIOX method (Simple Interactive Object Extraction).

33. Transform Tools • Move Tool • Crop Tool • Rotate Tool • Scale Tool • Shear Tool • Perspective Tool • Flip Tool

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

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

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

37. 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.

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

39. 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.

40. GIMP Resources • GIMP documentation:http://docs.gimp.org/en/ • GIMP Tutorials:http://www.gimp.org/tutorials/