These filters allows you to adjust the color of an image or a particular area of an image. The easiest way to adjust the level, contrast, color balance of an image is to use 'Auto~' filters.
Auto Level filter analysis the histogram of each RGB channel of an image and automatically modifies the intensity range of each channel. The following image shows the appearance of the image that is applied auto level filter.
Auto Contrast filter automatically modifies the color contrast of an image.
Auto Color Balance filter automatically modifies the color balance of an image.
The following images are pictures of the "Dosirak" in a restaurant. It shows differnet colors affected dark lighting in restaurant unlike original colors. In this case, you can easily to correct an image by applying the above filters.
Level filter allows you to change the intensity range of an image. Level filter is used to make an image lighter or darker, to change contrast using following options: a min point, max point and mid slider. You can redefine the histogram's "Input Levels" using the min and max point and redefine the middle gray using mid slider.
You can change the specific channel which will be modified by the Level filter.
Curves filter allows you to change the intensity range of an image using curves. Unlike levels however, which only has min and max. You can redefine the mid-tone curves using points.
Color balance filter allows you to adjust color balance of the image.
Hue/Saturation filter adjusts the hue and saturation of the image.
Hue allows you to select a hue in the HSV color: -180 through - 180.
This allows you to select a saturation: -100 through 100.
This allows you to select a brightness: -100 through 100.
If this is checked, the colors are changed in same tone.
Invert filter inverts the image.
Threshold filter transforms an image into a black and white image. The pixels that have a greater brightness than threshold will be white pixel, and the other case will be black pixel.
This controls the threshold(0-255).
If you check here, you can change the threshold of each RGB channel.
Histogram equalize filter automatically adjusts the brightness of colors of the image.
Posterize filter allows you to change the number of levels of the image's color.
This controls the number of levels(2-255). The total number of colors is the combination of these levels.
The below sample image shows the posterized images in serveral levels. The first image that anchored left top of an image is posterized in 2 levels. A level to 2 will give 22(=4) colors: white, cyan, blue and black. As the level increase, so increase the number of the colors.