I have a few questions about using the color correction filters in VS9.
1) What is Gamma? In tryingits preview slider, itseems to act much the same as brightness-moved to the right the image gets more bright, to the left it gets darker. However, I assume it is not the same as brightness, or why would it be a separate control? And I'm not sure the preview gives a full picture of what the gamma control actually does. For what reasons would one use the Gamma control, to move it above or below the default level of 0?
2) I experimented some with these color correction controls on a video. With my settings, the clips certainly looked better in the preview window, than with the default 0 settings for the controls.
I saved to a new MPEG file. I indicated to keep the same MPEG settings as the input (MPEG-2) video. I had SmarRender selected. I assumed that, keeping the MPEG-2 settings the same, there would be no need for recompression, and it would render quickly. But unfortunately, it took several hours to create the new .mpg file.
If one uses those filters, is recompression unavoidable--a complete re-rendering--no SmartRender, etc., when one uses any of those filters (hue, saturation, brightness, contrast, gamma)? Or only with certain of those filters?
3) (See 2 above.) The resulting .mpg file was MUCH larger than the original! In fact, over 50% larger! Yet the videos are of course the same length, and show the same bit rate, as I indicated to keep the .MPG settings of the original file, in the new one. Both show the bit rate of 8000 kbps. Now, I thought file size was only determined by bit rate and length of video. Bits per second multiplied by amount of seconds in video=file size (approximately, at least). Why was my color-corrected video so much larger than the original?
4)(See 2 above.) Although the preview in VS7 definitely looked much better with those filters added (good that it is per clip, as each clip might need different correction), the resulting video looked worse than the original. How did that happen? Is what one sees in the preview window (of the color correction filter) not very accurate, not very indicative of what the final result would look like? (If so, if anyone from Ulead is reading, I would suggest you improve the accuracy of that preview window.) Anything the user can do to make it more accurate. It looks like I will have to change settings, and take another several hours to render again. Oy vey!
I would appreciate any help with these questions. Thank you.
Using the Color Correction filters in VS9
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Dear me (thought I'd start off with a little joke to lighten the mood!)
1. Think of Gamma as brightness for video displays, it's easier that way and gives you a working idea.
2. It's not until well into your post that we find that you are editing MPEGs. Now there is a lot of discussion regarding that point as to whether it can/should be done or not. Personally, I merrily hack the hell out of them using transitions, cuts, multi-trims, add sound, overlays whatever and have had no problems as long as I follow the procedure outlined in the sticky at the top of the forum.
BUT!!!! Applying filters is one thing that does not always go well and usually goes badly. As soon as you apply a filter you will cause an already compressed file to be totally re-rendered and the results are very unreliable. (And it takes a long time doesn't it!) The preview screen can only give you a rough guess as to what the final MPEG is going to look like because until you render who know what is going to happen with the file.
1. Think of Gamma as brightness for video displays, it's easier that way and gives you a working idea.
2. It's not until well into your post that we find that you are editing MPEGs. Now there is a lot of discussion regarding that point as to whether it can/should be done or not. Personally, I merrily hack the hell out of them using transitions, cuts, multi-trims, add sound, overlays whatever and have had no problems as long as I follow the procedure outlined in the sticky at the top of the forum.
BUT!!!! Applying filters is one thing that does not always go well and usually goes badly. As soon as you apply a filter you will cause an already compressed file to be totally re-rendered and the results are very unreliable. (And it takes a long time doesn't it!) The preview screen can only give you a rough guess as to what the final MPEG is going to look like because until you render who know what is going to happen with the file.
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GeorgeBW
Hi Guys,
I have also had occasions when the whole issue of displaying imagery accurately on a PC Monitor has been a tormenting challenge. When you think about it, there are so many variables that need to be taken into account... Some of these are perhaps entirely out of your control such as the quality of the original video or photograph... and the eventual TV system that might be displaying a factored DVD or Photo CD.. Essentially Gamma is a Brightness and Contrast correction... small changes in value will equal what seems to be disproportionate changes in image appearance. Beware, adjustments will affect colour too.. and Blues/Greens ..hue and saturation can begin to appear out of balance against Reds/Magentas. If you have to start compensating with these filters too, you can easily end up with the proverbial Pigs Ear. The settings will not be the same for PC Monitor or TV output, as these display in entirely different ways. Best left at the default values contained in the software, unless you have the expertise to know how to adjust this filter.
It is also wise to remember, that every filter applied needs every pixel of every frame, of every clip that it applies to, to be re-rendered.. A full to capacity DVD could take a long long time..
Mind snapping stuff... ideally something to be kept simple, but if you want to read up more.. Do a Web search.. just type Gamma into your search engine... or try this link for starters..
http://www.cgsd.com/papers/gamma_intro.html
Good luck
George
I have also had occasions when the whole issue of displaying imagery accurately on a PC Monitor has been a tormenting challenge. When you think about it, there are so many variables that need to be taken into account... Some of these are perhaps entirely out of your control such as the quality of the original video or photograph... and the eventual TV system that might be displaying a factored DVD or Photo CD.. Essentially Gamma is a Brightness and Contrast correction... small changes in value will equal what seems to be disproportionate changes in image appearance. Beware, adjustments will affect colour too.. and Blues/Greens ..hue and saturation can begin to appear out of balance against Reds/Magentas. If you have to start compensating with these filters too, you can easily end up with the proverbial Pigs Ear. The settings will not be the same for PC Monitor or TV output, as these display in entirely different ways. Best left at the default values contained in the software, unless you have the expertise to know how to adjust this filter.
It is also wise to remember, that every filter applied needs every pixel of every frame, of every clip that it applies to, to be re-rendered.. A full to capacity DVD could take a long long time..
Mind snapping stuff... ideally something to be kept simple, but if you want to read up more.. Do a Web search.. just type Gamma into your search engine... or try this link for starters..
http://www.cgsd.com/papers/gamma_intro.html
Good luck
George