Secondary : No
Uses colour : No
Options : Gamma adjustment value (-256 to 256)
Description :Gamma alters the brightness of the image based on a gamma curve. This keeps the darkest areas dark, the brightest areas bright, but raises or lowers the brightness of the image in between. With higher Gamma values, the midtones become brighter, with lower Gamma values the midtones become darker.
Secondary : No
Uses colour : Yes
Options : Position (percent), Smoothness (percent)
Description :Simulates the two-tone filters produced for photography that are coloured on one half of the filter and clear on the other half. These are often used to give skies deep colours (simulating a sunset or making a light sky a deep blue) without tinting the rest of the landscape. This paint mode is very powerful as you can specify both the position of the halfway mark (the boundary between the coloured portion and the clear portion) and the smoothness of the join - at 0% it is a sharp transition between coloured and clear, at 100% the transition is totally smooth.
Secondary : No
Uses colour : No
Options : Conversion type.
Description :Convert to grey scale. There are several different algorithms you can select from to create your grey scale image.
The image is converted using a standard algorithm where the different colour components (red, green and blue) are mixed together based on their comparitive brightness. This will give an accurate rendition of the image to greyscale.
The red, green and blue components are added together and divided by three. This is faster than Video Weighting, and sometimes gives a more pleasing result.
The greyscale image is created by selecting the brightest of the red, green and blue colour components. This generally gives a brighter image, but some colours (eg. blue) may convert to unexpectedly bright areas in your grey scale image.
The darkest of the three colour components (red, green and blue) is used as the new grey scale component. This usually gives very dark images, and may result in large black areas!
The median of the three colour components (ie. when arranged in order of brightness, the middle value is chosen) is used for the grey scale image. This usually results in some areas being much brighter than expected and others being darker than expected.
Only the red component is used for the grey scale conversion. Red filters used in black and white photography are often used to subdue ambient light and to make clouds more brilliant.
Only the green colour component is used. Green filters are good for converting portrait photos to grey scale - the colour of skin and lips is slightly darkened.
Only the blue colour component is used for the grey scale image. Blue areas remain bright, red and green areas turn black.
The blue and green colour components are averaged for the grey scale image. Any red in the original image turns black.
Only the red and blue components are used for the grey scale image. Any green in the original image will turn black.
The yellow filter is another popular photographic filter. Contrast is improved in landscape images and skin tones are lightened and freckles are softened.