|
Source: (largely custom); [FOLE90:590-593]
Hue / saturation is another point process filter implemented based on a similar function in Photoshop®. This filter allows modification of each of the H(ue) S(aturation V(alue) components of the HSV pixel. Here, obviously, we will also use the RGB / HSV conversions talked about in the grayscale filter. The algorithm is quite simple:
for every pixel in the image do
{
hsvpixel = currentpixel;
hsvpixel.h += somevalue1;
hsvpixel.s += somevalue2;
hsvpixel.v += somevalue3;
filterpixel = hsvpixel;
}
The filter dialog box allows the user to increase or decrease each component of an hsvpixel. All the program has to do is convert the current pixel to HSV, apply the increases or decreases, and retranslate back to
RGB.
There is an option to ‘Colorize’ the image in the hue / saturation dialog box of FilterExplorer. Checking this box simply uses the same hue (as specified in the dialog) for every pixel. So instead of increasing or decreasing the pixel’s hue, it simply assigns it a new hue.
Hue / Saturation with colorize:
Hue = -140, Saturation = -40, Brightness = -20
Return to
the list of filters
|
