neily
15th October 2004, 12:23
Hi,
I've been playing around with trying to transfer onto DVD some old video footage, some from a webcam, some in Div3. I know, I should have bought a camcorder initially, and having done so should not have reused my tapes, but lesson learnt.
Anyway, whilst trying to correct this stuff to something reasonable, I have found this anomaly with ColorYUV. If you use a single ColorYUV filter with parameters PC-TV and Gain, the output is the same as doing a gain, then PC-TV. However if you do the same for AutoGain and PC-TV, the results are different to doing then seperately in either order. For instance, the results for min/max/loose min/loose max for one particular frame are:
AutoGain + PC-TV 8/221/28/218
AutoGain then PC-TV 16/225/31/220
PC-TV then AutoGain 0/242/17/236
So can anyone explain what the order of execution of gain/contrast/offset/gamma, Levels, and AutoGain are in ColorYUV, and why I get the results above.
Now for the request/suggestion. What about a filter or extension to ColorYUV that takes a simple text file as input as the basis for the ColorLUT? That way it would be fairly simple to produce an external applet that can generate the LUT using any manner of curves, thresholds etc. I'm thinking of a simple input output:
0,0
1,2
2,3
etc
It seems most desirable for Y, but I suppose could be implemented for U and V as well.
I've been playing around with trying to transfer onto DVD some old video footage, some from a webcam, some in Div3. I know, I should have bought a camcorder initially, and having done so should not have reused my tapes, but lesson learnt.
Anyway, whilst trying to correct this stuff to something reasonable, I have found this anomaly with ColorYUV. If you use a single ColorYUV filter with parameters PC-TV and Gain, the output is the same as doing a gain, then PC-TV. However if you do the same for AutoGain and PC-TV, the results are different to doing then seperately in either order. For instance, the results for min/max/loose min/loose max for one particular frame are:
AutoGain + PC-TV 8/221/28/218
AutoGain then PC-TV 16/225/31/220
PC-TV then AutoGain 0/242/17/236
So can anyone explain what the order of execution of gain/contrast/offset/gamma, Levels, and AutoGain are in ColorYUV, and why I get the results above.
Now for the request/suggestion. What about a filter or extension to ColorYUV that takes a simple text file as input as the basis for the ColorLUT? That way it would be fairly simple to produce an external applet that can generate the LUT using any manner of curves, thresholds etc. I'm thinking of a simple input output:
0,0
1,2
2,3
etc
It seems most desirable for Y, but I suppose could be implemented for U and V as well.