Color Equalizer

Old video cameras sometimes have wrong color-balance, which causes a little bit colored video recordings. The image sometimes is a bit bluish, sometimes has pink color. This effect is extremely annoying at a digitally archived recording, but it can be compensated by a digital color equalizer filter.

The Color Equalizer was designed to be a simple, robust VirtualDub filter which has an easy-to-use interface. This filter can amplify separately the red, green and blue components of the images and can shift them separately with an offset value. The transformation can be seen in the following equation: C=A*C+O, where C, A and O are the color (red, green or blue), amplification and offset values respectively.

During the equalizing process, the transformed color values are taken from a look-up table. This method provides good speed. The look-up table is computed at the filter initialization process with 32-bit fixed point integer arithmetic. This computation method does not affect the accuracy of the LUT.

The transformation process has a saturated characteristics: if a transformed color value is out from the range of 0-255, then the transformed value will be 0 or 255. The compiler program was tuned for speed and for Pentium class computers. The compiled DLL unfortunately does not contain MMX optimization. This v1.1 version of the program contains already a preview window and a reset button.