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"Color Correction" bug - adjusting Gamma shifts Black level

Last post 08-16-2011, 17:38 by culpanr. 0 replies.
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  •  08-16-2011, 17:38 487170

    "Color Correction" bug - adjusting Gamma shifts Black level

    Affects the "Color Correction" plugin found in Studio Plus/Ultimate ("Studio Plus RTFX | Color Correction" or "Studio Ultimate RTFX | Color Correction"). Bug found to exist when using the plugin in Studio 11, 12 and 14 (cannot test with Studio 15 as I don't have it...).

    Bug details - when adjusting Gamma within the plugin, the Black point also shifts, resulting in loss of the darkest tones of the image and they take on a murky appearance.

    To reproduce:
    1. Take a pure black bitmap image or create a title having a solid black background (RGB 0, 0, 0) and add to the project.
    2. Apply the "Studio Plus (or Ultimate) RTFX | Color Correction" filter
    3. In the filter's controls, scroll down and find the three sliders "Gain" / "Gamma" / "Black" in the "Intensity Correction" section
    4. Move the "Gamma" slider to the right and the solid black title/image becomes grey.

    And, if you try with a gradient fill (going from Black to White), increase "Gamma" but then try to get rid of the black-level shift by moving the "Black" slider a little to the left, you will see that the "blacks" then get clipped; it is not possible to remove the unwanted "shift" without losing some detail in the dark parts of the image.

    This is IMO just plain wrong and a bug - the two ends of the "Gamma Curve" should be tied to (0, 0, 0) and (255, 255, 255) and not move; altering the "Gamma" value should just alter the "curvyness" in between. It should NOT shift black or white levels or cause blacks/whites to become clipped.

    Workaround for now is to use a third-party filter such as JPsEffects; however that filter is considerably slower than Studio's own one (especially on HD material).

    Regards,
    Richard

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