1. Drawing in GIMP GIMP User Manual

2. Lesson Overview Understand how new graphical content can created by combining free-hand techniques with existing image content Become familiar with some common graphics terminology: dithering, anti-aliasing, haloing, color modes, and alpha transparency Learn how to use the basic drawing tools and options of a graphical application like GIMP Extend the capability of GIMP to create vector like shapes using the Gfig dialog

3. Some Drawing Terminology Dithering Anti-aliasing Haloing Color Modes Alpha Transparency

4. Dithering Dithering is a technique used in computer graphics to create the illusion of more colors when displaying an image which has a low color depth The missing colors are reproduced by a certain arrangement of pixels in the available colors The human eye perceives this as a mixture of the individual colors Dithering increases the size of an indexed formatted image The Gradient Tool in GIMP uses dithering

5. Dithering and Indexed Format When converting a GIMP image from RGB format to Indexed Format you may choose dithering to smooth banding effects Both GIF and PNG formats can use indexed color

6. Anti-Aliasing When rendering an edge at an angle, it will look “jagged” because of the nature of pixels Anti-aliasing tries to make the edges look smoother by giving the boundary pixels a color between the image and the background image The human eye then blends the two colors on either side Good for text in graphics Adds to the file size

7. Haloing Haloing is undesirable effect that is created when using transparency Caused because the edges of an anti-aliased object, such as text, are not purely the background color, they have been blurred When the background is made transparent, these blurred pixels still show up

8. Preventing Haloing If possible, set background color to your planned web page background color If you want transparency in the background, set this before drawing any shapes or text You can also turn off anti-aliasing for a drawing tool or selection tool

9. Color Modes in GIMP True Color (RGB) Millions of colors Grayscale The grayscale mode uses one channel to display a gray image Indexed Color The image consist of pixels picked from a palette of up to 256 colors By converting to this mode you are reducing the color depth of an image

10. Color Mode Menus Menu items for color modes: Image > Mode > RGB Image > Mode > Grayscale Image > Mode > Indexed

11. Alpha Transparency Regardless of the mode, images can have an optional alpha channel for transparency By enabled by alpha channel, you can create a picture by stacking several layers on top of each other, save images for the web, or create images for 3D graphics that have holes or semi-opaque areas Use GIF as a Web format to supports fully opaque or fully transparent images

12. Alpha Transparency Menus Menu items for alpha channel: Layer > Transparency > Add Alpha Channel Layer > Transparency > Remove Alpha Channel Layer > Transparency > Add to Selection

13. Drawing in GIMP Most drawings begin with a blank canvas Choose the image size and background color Always create a layer for each figure in your drawing This allows you to duplicate figures and change background color if necessary Name each layer for the main figure on the layer

14. Drawing Techniques in GIMP Drawing lines and curves Changing colors and brushes Drawing circles, rectangles, and other shapes Using a filter to draw temporary vector graphical objects Outlining and filling regions Filling with patterns and gradients

15. New Image Always start with an existing or a new image Set the background color or make it transparent Create a new layer for each functional unit of your drawing Name the layer with a meaningful name

16. Drawing Lines and Curves Use the Pencil tool to create hard-edged lines To draw a free hand line, hold down the left mouse button and drag the mouse where you want. To draw a straight line, click the first point, hold down the shift key, then click the last point. The pencil will have a round point determined by the brush that is selected To turn off the brush size in the cursor, go to Edit=>Preferences=>Image Window and set Mouse Pointer Pointer Mode to be Tool Icon with crosshair or just crosshair

17. Pencil Line Drawing

18. Brushes Changing the brush gives you control of the width and shape of the lines you draw with any of the GIMP drawing tools There are several ways to change brushes Click on the brush circle in the toolbox brush icon or choose to show the brushes panel from the Windows=>Dockable Dialogs=>Brushes menu

19. Change Brushes Changing a brush type is easy Just click on the brush icon to bring up the Brushes Panel Click to View

20. Brushes Panel There are many types of brushes to choose from Just click to choose a different brush

21. Animated Image Brushes Some built in animated image brushes can be selected You can vary the spacing The fixed color ignores current foreground or background colors

22. Importing Abobe Brushes There are many brushes available on the Internet One standard format that can be imported into GIMP are Abobe brushes. These are usually available in zipped files The extension are.abr for Adobe brushes Loading too many brushes will make GIMP take a long time to start

23. Brusheezy.com – This web site has many Adobe brushes available with unrestricted use requirements Download the zipped file Extract the.abr files Place in your GIMP brushes area: C:/ProgramFiles/GIMP- 2.0/share/gimp//2.0/brushes/

24. Custom Brushes Custom brushes you load can be drawn like a line or stamped to create an individual image You can usually size the brush, choose a color, set opacity or other brush attributes Don’t be afraid to experiment with these custom brushes, you can always undo and try again

25. Image made with Adobe Brushes

26. Parametric Brushes Parametric brushes are based on a mathematical representation of a shape like round, diamond, or square Use the Brush Editor dialog to create a new brush with the following: Radius Hardness Aspect Ratio Angle Spacing

27. Drawing Tool Options All the line drawing tools have similar options: Opacity – percentage of transparency Mode – special drawing modes Fade out – line fades over a distance Incremental- only if opacity is < 100%, will make a line darker if repeated Use color from gradient – Uses gradient instead of current foreground color

28. Pencil Drawing Options Chose to use color from gradient

29. Special Layer Drawing Modes Normal Dissolve Behind and Color Erase modes needs a top layer with an alpha channel (transparency)

30. Fuzzy or Smooth Lines? The pencil tool draws hard-edged lines but has jagged edges Not anti-aliased by default The paintbrush tool draws fuzzy lines with the brushes These lines are anti-aliased The edges are semi-transparent and are blended with the background color The paintbrush can also use hard-edged brushes

31. Aliased or Anti-Aliased Lines Pencil Lines Paintbrush Lines

32. Airbrush Tool This tool always draws a fuzzy edge, even if a hard-edged brush is selected The airbrush is time sensitive, the slower you go, the darker it draws The Rate controls how sensitive the tool is to movement The Pressure controls the darkness. Think of this as the amount of paint the airbrush is spraying

33. The Calligraphic Brush This tool mimics a real calligraphic pen or brush Choose the airbrush tool, then select a calligraphic brush The path of the line changes depending of the orientation of the brush Uses the same options as the airbrush tool, rate and pressure

34. Ink Pen Tool This tool emulates an old fashioned fountain pen Has different shaped nibs or point types Ignores other brushes Has its own notion of a brush

35. The Ink Pen Tool Adjustment controls the width of the nib and its angle Sensitivity controls how much ink is released Type controls shape of nib The Shape box allows dragging of square to change shape

36. The Eraser Tool If the current layer has an alpha channel, the layer supports transparency, then the eraser will work The eraser uses the current brush to affect its shape You can zoom to magnify the image to control erasing at the pixel level Can erase with a hard edge or a soft edge

37. The Erase Tool

38. Drawing Shapes GIMP is not a vector graphic drawing program The Gfig Filter allows some vector graphic shape drawing capability (More later on this!) Use a selection tool and then fill or stroke the selection to make your own shapes

39. Outlining Selections: Stroking Draw a selection with either the rectangle, ellipse selection tools Open the Stroke Selection dialog once the selection is active by Edit=>Stroke Selection Set the Line Width, the Line Style or choose a paint tool if wanted Then click the Stoke button

40. Stroking a Selection Rectangle selection Line Width 12 Line Style was a wood grain Pattern

41. Free Select with the Lasso Draw any shape with the Lasso tool You can use the Stoke Selection dialog to stroke the edge of the selected area Use Edit=>Fill with FG Color to fill the selection with the current foreground color You can also fill a selection by dragging the forecolor or background color pattern swatches into the image

42. Free Select Tool Selection Create selection using the Free Select Tool (also called Lasso) Stroke Selection using Paintbrush Fill color using Fill with FC Color

43. Fuzzy Selection Tool Also called the Magic Wand This tool allows selection based on color similarity The Threshold option can be used to broaden the selection to touching pixels

44. Selection using Fuzzy Select

45. Paths Tool The Paths Tool allows you to create complex selection known as Bezier Curves You can edit your curve, add or delete points

46. Paths Tool Example

47. Bucket Fill Tool Use this tool for more complicated color filling Opacity and Mode are the same as with other tools Fill Type lets you fill with FG, BG, or Pattern Holding will reverse fill type

48. Bucket Tool – Affected Area Check to Fill similar colors The Threshold slides controls just how similar the colors will be This may take some experimenting to get it right

49. Patterns A Pattern is just an image Patterns are usually tileable, repeatable Use the Pattern swatch to set the Pattern you want Patterns can be edited and saved as a new Pattern

50. Adding New Patterns Create your own pattern and save it with a.pat extension Find a pattern with a.pat extension such as those at www.Brusheezy.com Place in your pattern file in this area: C:/ProgramFiles/GIMP- 2.0/share/gimp//2.0/patterns/ Open GIMP again and the pattern should be available

51. Gradients The Blend tool is another way to fill areas Set the Opacity or Mode Choose a Gradient Choose a Shape and Offset

52. Gradients With the blend tool selected, mouse down in a selection and drag in the direction you want the gradient to flow

53. Reverse Gradient Use a selection tool like the lasso to draw the selection Choose a Gradient and then click the Reverse box Use your mouse to drag the direction you want

54. Vector Graphics with Gfig A special filter called Gfig can be used to create a layer with vector graphics After drawing your shapes, close the Gfig editor and you will now have a layer in your drawing You can save your Gfig drawing and reopen it at another time Go to the Filter=>Render=>Gfig

56. Vector Graphics Converted After closing the Gfig editor The vector graphics are converted into raster graphics They have their own layer

57. Modify Gfig Layer The Gfig shapes are now just pixels on a layer They can be selected, transformed and moved

58. Summary Use the various tools and brushes to create the drawing you want Fill the shapes and add stroking to control the edges Use the Gfig filter to draw vector graphic shapes if you need to You can use these techniques to draw anything you can think of, with patience and a lot of layers