This filter dynamically scales pixel RGB levels in order to fully utilize the 0-255 range, which gives optimum brightness and contrast.
Many source movies have little contrast and don't utilize pure black (0,0,0) or pure white (255,255,255) (see 'before' picture below). By offsetting and scaling the RGB histogram each frame, this filter can provide an output much easier to see (see 'after' picture below).
Note that while most filters to set brightness / contrast provide only one universal setting for the whole movie, this filter dynamically tracks the source RGB histogram and provides the best settings for each scene / shot. In addition smoothing is applied to prevent 'flicker' occurring when a scene shows rapid changes in the input RGB histogram.
Now with live preview.
Clip highlights percentage: Determines the percentage of pixels that are allowed to clip the 255 level. Usually this is best set to a lowish value, around 1 percent, in order to prevent clipping distortion of the highlights. However, setting a reasonable amount higher than zero is advisable to prevent spurious highlights (e.g. noise) affecting the results.
Clip shadows percentage: Determines the percentage of pixels that are allowed to clip the 0 level. With movies that fit the entire frame this can be set to a low value (e.g. 1 percent). However, when a movie contains black borders, the clip shadows percentage should be raised in order to 'ignore' and compensate for the borders, which are not part of the real image.
Preview clipped: Switches the filter output to a preview mode which enables easy visualization of which pixels are being clipped. Gray pixels are not being clipped at all. If either the R, G, or B is being clipped on the lower boundary it is assigned 0. If either the R, G, or B is being clipped on the higher boundary it is assigned 255.
Highlights min: Minimum value between 0 and 255 that the filter will adapt to for highlights. This can be used to prevent very dark frames from becoming too lightened (e.g. black screen between credits).
Shadows max: Maximum value between 0 and 255 that the filter will adapt to for shadows. This can be used to prevent very light frames from becoming too darkened (e.g. closeup of the sun).
Please send feedback to
coverme_imgoingin@yahoo.co.uk
VirtualDub homepage:
http://www.virtualdub.org/
This filter can be freely distributed, as long as it is provided 'as is' in the original zip file. This version is free to use for both non-commercial and commercial purposes. I intend to release the source code under the gpl after a bit of beta testing. Enjoy! :)
Scrambled
March 1, 2006
© Copyright 2006 Scrambled, All Rights Reserved
On no account will the author accept liability for any negative consequences of using the software, including but not limited to loss of data, infection by viruses, hardware damage, loss of time. If you are unable or unwilling to accept full responsibility and liability for the use of the software, then you must immediately delete it.
This version of 'the software' is granted free of charge for non-commercial or commercial use. In case of integration with commercial software, prior author permission must be obtained. 'The software' must not be modified and distributed without prior permission of the author. By using 'the software' you agree to the licensing terms.
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