Colour Quadrant Correction


Utilities in this section could be used in conjunction with output from the current favoured Colour Recovery software, from the work of Richard Russell.

Resultant colours can sometimes be decoded with respect to the wrong U/V colour quadrant. A quadrant correction utility enables manual adjustment of areas of picture that have been decoded to an incorrect quadrant. Generally, patches of affected colour occur, and they align with the block pattern used within the CR software that Richard contributed.

If a coloured area lies within the incorrect quadrant, this of course means that the correct quadrant is one of three others.
The correct quadrant can be obtained simply by changing the sign of the colour values in the affected area: i.e. changing the sign of U, the sign of V, or the sign of both U and V.

The workflow (within a GUI environment) is:

i) Select a UYVY video file to be the subject of correction.
ii) Navigate through frames in the file, and display an individual frame from the file which (the eye determines) contains a problem area (or areas).
iii) Click on a problem area to correct. The first click defines the borders of the problem area in an X, Y (and possible Z) dimension. Each subsequent click which cycles through the four possibilities for quadrant signage. On each click, the values in the defined area change to reflect the new signs and are displayed within the image shown.
iv) Navigation away from the adjusted frame means the adjustment is persisted, and the workflow goes back to step (ii).
v) Save the corrected UYVY file.

The development of Colour Quarant Correction utilities posted here are written up under the 'Previous Work' section, as finished utilities are posted here within the 'Utilities' section.

James Insell 15/02/2009