Menu Mode

This menu is a list of the different drawing modes. Commonly whenever you draw with the foreground color (drawing with left mouse button) the mode you have chosen here will be used. This mode also affects drawing primitives like lines, rectangles, circles...
Whenever possible the right mouse button uses an inverse operation like darken if the mode is Brighten.
Some paint modes do color calculations. Because there are only 256 colors that can be used the quality of the result may be poor if your palette does not contain proper entries. The more colors of different kind your color table contains the better the results will be.
Some paint modes can be configured using the Settings... menu entry.

Besides selecting a paint mode from this menu you can use the shortcuts as displayed for every menu entry. To increase workflow speed you can hold the key shortcut and draw. If you then release it the previously selected mode will be enabled again. This way you can for example quickly select "Erase" because this is typically something you don't do permanently.

Paint

Paints with current brush as it is. That means the brush is simply stamped down.

Erase

Uses the transparent color for painting if there is no alpha plane. If alpha is enabled then the left mouse button reduces the opacity by the given value where the right mouse button draws fully transparent. In detail it works like this:
Project has simple or no transparency
  any mouse button= transparent color if layer is transparent or project background color if it is not
Project has alpha transparency   left mouse button= decrease alpha by selected opacity
  right mouse button= set zero alpha

Selection

Instead of modifying pixels this mode will modify the selection. This way you can apply the drawing selection easily using any drawing tool. The left mouse button includes and the right excludes for selection.

Halftone

Uses the currently selected dither pattern for drawing. It will use the selected foreground and background color with the pattern.

Brightness

Brightens image colors with left mouse button and darkens with the right. You can set the strength of brightening in the Settings.

Tint

Tints image colors with brush colors. That means the brightness of each image pixel is taken and the color from the corresponding brush pixel. Both are mixed together and the result is a pixel with the brush pixel color and the image pixel brightness.

Inc/Dec Hue

Takes the Hue (color model HSV) of the image pixels and rotates it (0..360°). You can set the strength of this mode in the Settings

Inc/Dec Saturation

Increments/decrements the Saturation(color model HSV) of the image pixel colors. You can set the strength and type of this mode in the Settings

Invert

Simply inverts the image colors using the RGB-color model. A Red value of f.e. 40 will then be 215 (=255-40). The mode will try to find the best matching inverse color in the palette.

Difference

Uses difference values between image and brush colors for painting (RGB color model).

Translucent

Mixes image and brush colors. You can define a proportional weighting for this mode. That means the result color is calculated by x% of the image color and y% of the brush color and x+y=100%. See the paint mode Settings below.

Color Cycle

Uses the colors of the current gradient one after another. If the last gradient color is passed the first one is used again...

Gray

Reduces the image colors to gray levels.

Rub Through

When drawing with this mode the image that resides in the "Spare Frame" (see descriptions for menu Frame) becomes visible. You "rub through" to the spare frame.

Shade

Shifts the image colors which are part of the current gradient. So for each color the next or previous color within the gradient will be used depending on left or right click. This way you can shade objects to emphasize their structure, to create different color effects or to smooth edges.

Multi Shade

Works the same as Shade but uses mor than a single gradient at a time. It only works for gradients that are set up for multi shade paint mode. Because you might want to have gradients that are not touched by the multi shade you must enable a gradient that may be used. Just go to the gradient editor and activate multi shade paint mode for the gradients that may be used for this paint mode.

Paint single Color

Draws using current foreground color regardless if the brush has more than one color.

Replace

Draws with the current brush but without transparency. Instead it is stamped down as is.

Smear

Smears the colors in the drawing direction. Only use with continuous painting or continuous line modes.

Blend

Smears the colors in the drawing direction and applies smoothing. Only use with continuous painting or continuous line modes.

Formula

This mode can be used to modify pixels using different types of mathematical formulas. See Settings for further information.

High Pass

Increases brightness contrasts.

Soften

Softens color contrasts and makes the image blurry.

Soften more

Stronger soften mode.

Light Edges SE

Emphasizes edges that are nearly parallel to south, east or south east direction.

Light Edges NW

Emphasizes edges that are nearly parallel to west, north or north west direction.

Emboss I

Puts dark colored areas into the "background". So the objects look embossed.

Emboss II

Puts light colored areas into the "background".

cosmigo

Documentation