Sony Vegas Rendered Files Are Darker Than Original

[enbidia]

Below is comparison of a tiff image file opened in Photoshop and Sony Vegas 6. Any idea what is going on with Vegas why it cannot preserve the RGB values?

[JohnnyMalaria]

At first sight, these look the same. To be more objective, I have measured the RGB values for both of the test images taken from your screen shot. Apart from the three grey levels, the Vegas and Photoshop images are very comparable (the linear fit is forced through zero). I've attached a graph of the Vegas grey levels plotted against the Photoshop grey levels (taken from the grey bars part of the test image).

If the image looks darker overall (not just at the very dark end), it is probably an optical illusion caused by whatever else is on the screen surrounding the image.

Why the three darkest grey levels (excluding black) are lower most likely has to do with the rounding errors that will occur on small values in the conversion of RGB to YCrCb and back again (assuming you are looking at a frame from a rendered DV file, for example).



The other possibility - and I cannot tell from the screenshot - is if Vegas is rendering to a DirectX surface on the screen. Usually, a standard screenshot (via Print Screen) would show a blank area but not always. When a DirectX surface is being used, the graphics card draws the image independently from Windows and it is quite common for the graphics card to be able to be configured to use different brightness/contrast etc for that part of the screen than the rest. So, it may look darker on your system.

[dipstick]

Did you render it using the Sony DV codec? If yes, that is likely the reason. I've done numerous tests rendering Test Charts using diferent codec. Sony DV Codec consistantly blew out whites in my tests. MainConcept DV, Lagarith and Huffyuv got them correct.

Test render to different codecs to see if that's the problem in your case.

[enbidia]

Its hard to believe the quantization errors are as high as 3 RGB luminance levels. It has nothing to do with DV codec because this is just a tif image image file open directly in Sony Vegas but with shadows, midtone and highlights being altered it. It increases the contrast of both highlights and shadows. Cannot the RGB values be exactly followed?

ps. here is the test image I use:
http://i26.photobucket.com/albums/c113/ciecam97/MonitorChecker_lab.jpg

[edDV]

Its hard to believe the quantization errors are as high as 3 RGB luminance levels. It has nothing to do with DV codec because this is just a tif image image file open directly in Sony Vegas but with shadows, midtone and highlights being altered it. It increases the contrast of both highlights and shadows. Cannot the RGB values be exactly followed?

ps. here is the test image I use:
http://i26.photobucket.com/albums/c113/ciecam97/MonitorChecker_lab.jpg

Enbidia, I'm not seeing it. I loaded your first still back into Photoshop, cropped and put the left and right on the vegas timeline and got this result. Is this showing your issue?





Problem one: you are working over the full 0-255 range while Rec-601 DV DVD MPeg2 uses 16 for black and 235 for white.

[edDV]

This is your original MonitorChecker_lab.jpg on the vegas timeline.

[enbidia]

Thanks, I believe I made a mistake. I think why the captured RGB values in Photoshop look different to captured RGB values in Vegas or other graphic applications like MS Paint is because of the monitor ICC profile I use which Photoshop converted to it when displaying images. The RGB values do match now to Vegas when I open directly the original MonitorChecker_lab.jpg