Video Adjustment Tips Using Vegas Video

Preliminary Steps

Prior to applying filters you should divide your source file into events that have similar lighting levels and hue characteristics. You can then effectively use Video FX filters which can dramatically alter the appearance of your video. The online help system provides step by step instructions on how to divide your source file into Events. As you work through your source file it is strongly advised that you make frequent saves of the Vegas Video veg file so if you suffer a system crash you won't lose more than a small portion of the work you've already done. Every ten minutes or so depending on your comfort level and how many changes you've made, click File, select 'save as' and save a copy of the veg file. Instead of overwriting the same file,over and over, your first save could simply be called A.veg, followed by B.veg. And so on. Making repetitive copies also allows you to play 'what-if' and return your project to an earlier state easily without redoing your work. There is no need to repeatedly save your source files. In fact the source file should remain unchanged by you throughout the entire editing process. All editing is completely nondestructive to your source file with the veg file containing all the information necessary for Vegas Video to apply the changes you've made once you're ready to render.

If the finished video is to be played off a television, it is important that you use an external monitor during the color and level correction phase of your editing so you will make adjustments in 'TV colors and levels' as opposed to computer colors and levels which are very different. Details for connecting an external monitor and viewing the preview window from it are contained in Vegas Video's online help with more details in the full manual starting on page 234 which can be downloaded from the Sonic Foundry web site. It is also important that any external monitor you use to make adjustments plus any television you view your finished work on is properly calibrated. You should be aware that many people out of habit crank up brightness and contrast as well as focus or fine tuning on their TV sets which adversely effects overall picture quality. Using an external TV with video in capability should not be confused with using a second monitor to drag portions of your desktop to a second computer monitor. The following tips address some of the common problems that can be corrected by applying various Video FX filters either alone or in combination.

Image Too Dark, Lack of Detail

Image # 1 illustrates a common problem; a portion of your video is too dark which results in much of the detail being lost along with it having an orangish skin tone. In image #1 the subject in the foreground is of fair quality, however the skin tone and hair needs correction. Because the image is too dark his hair color is muddy and the shading is obscured. The background in nearly black blocking out the tree behind him on the left and the tractor wheel to the right.

As mentioned above, you should begin by breaking your source file into events that have similar problems. Once you work through your source file breaking it into events you're ready to begin applying filters.

For a video that is too dark your first step should be to correct the overall brightness (levels) of the image which frequently will reveal details you may not even be aware are hidden. By applying filter correction ahead of other editing tasks you may end up saving scenes you would have otherwise cast off as unacceptable due to poor video quality.

A good method to adjust overall brightness levels is to use the Levels Filters, beginning with Gamma. I changed the default from 1.000 to 1.200 with the results shown in image #2. If levels using gamma alone aren't satisfactory you can make further adjustments using the four other level sliders.

Image #2 after applying initial Levels adjustment. One simple adjustment already has made a large difference in what detail is visible. The tree trunk to the left and behind the boy is starting to be revealed, along with the wheel of the tractor. Both the skin tone and hair colors are better, but still not correct and will be adjusted in a later step.

What we want to do next is bring out still more detail and richness that's likely still hidden in the image. Frequently the best way is to use Color Curves which will allow you to adjust the three regions of the image (shadows, midtones and highlights) separately. If you try to adjust using Contrast and Brightness alone, all the pixels in the image get the same amount of adjustment which means more pixels end up getting adjusted than should be. Such a brute force method frequently results in a worse rather than better image. Most would agree the most important part of any image is normally contained within the midtone range. By using curves, you won't sacrifice the all important midtones. Using brightness alone tends to push too much of the midtones into the highlight range with the result the entire image being too bright. Using contrast alone tends to push midtones into the shadows resulting in an overly dark and harsher looking image. Cranking up brightness and contrast sadly can result in a loss of detail, exactly the opposite you're trying to accomplish. In fact you rarely need to use the brightness/contrast filter at all since much better results can be obtained using other filters which is what these tutorials are all about. While you can get good results using the presets that come with most of the filters, betters results frequently can be obtained by applying custom adjustments. The way to begin is drag the filter you're using to the event on the timeline you're adjusting and drop it. Then tweak the filter settings in the filter control box. If you want to apply the adjustment to the entire video, drag and drop the filter on the preview window.

Demystifying the "S" Curve (also see tutorials nine and after for more advanced color correction tips)

Making a "S" curve is ideal for adjusting the shadows and highlights regions without adversely altering the midtones. Applying a simple "S" curve allows adjustment of highlights, midtones and shadows separately thus allowing you to adjust only what needs adjusting as opposed to other methods that use a sledge hammer approach. The illustration at the left shows a typical "S" curve with the red diagonal line representing the initial starting point after dropping the Color Curves filter on the timeline with the black and gray lines the result of you manipulating it.

There are two basic methods for creating a simple "S" curve with Vegas. You can either drag the Tangent handles at either end of the initial diagonal line forming a curve in the line that way or right click on the line near the center then select create a point. If the image you're working on is either very light or dark shifting the position of the control point higher or lower on the diagonal line will effect shadows or highlights more than placing it close to center as will dragging the Tangent handles further away from the initial settings.

All images can be divided into roughly three broad areas. The top third of the graph adjusts highlights, the middle midtones, and the lower third shadows. To make a simple "S" Curve, left click your mouse on the control point you just created and while holding your left mouse button down slowly drag in the direction the arrow points. You'll notice that the midtones in the image start to lighten proportionally depending on how far you drag up and to the left. This is because the curve in the lower left is raising pixels in the shadows region more into the midtone range. How much and which pixels are effected the most is determined by the slope of the curve which is effected by the position of the set point or points you added.

You'll also notice since at this point the curve acts as a unit, pixels in the highlight region are decreased due the top half of the curve sloping down. This combination works in a similar way to applying the brightness and contrast filter, only you have much more control WHERE the brightness and contrast gets applied. Because pixels are also shifted you effect hue as well. With a little practice you'll learn to only effect the regions that need correction and not disturb those areas that don't as applying the brightness and contrast would.

Best results are generally obtained by moving on a diagonal. Dragging the center control point down and to the right has the effect of darkening. As you drag the control point you added far enough off its default position you'll see the tangent lines represented as lighter gray lines start to move away. By right clicking on the tangent boxes (the smaller light gray rectangles on either side of the larger control point you added) you can uncheck lock tangents which allows you to more precisely control highlights and shadows separately by sweeping the respective lines in an arc.. The lower tangent box control regions below the set point more. The upper controls highlights more. As you rotate either tangent note the effect it has on bending the curve as you watch the image in the preview window, preferably on an external monitor to get truer colors if your project is going to be displayed on a TV either played from a video camera or later burned to a VCD or DVD.

Image #3 after applying Levels and Color Curves adjustment. Now the rim and the sidewall of the tractor tire are visible including a couple bolts. The skin tone, hair and eye colors are more natural. If you look closely, the fence post hardly visible in the original is now seen along with the top wire along with some moss growing on the tree. Each source file will require a slightly different adjustment. The "S" curve shown is illustrative only and not the exact one used in these illustrations. Generally for darker images you want to begin with adjusting levels before you apply color curves. If your image is too light and washed out you may have better results if you first adjust curves. Regardless what you do first you frequently will end up with better results if you make further minor adjustments once color correction is finished which is explained in a later step.

At this point your image should be well balanced with a good distribution of pixels without any one area dominating, but may still lack overall fidelity. We will address that next by using the HSL filter as illustrated in Image #4.

Image #4 after applying Levels, Color Curves and HSL. By slightly reducing the saturation to .88 and increasing the luminance to 1.03 we have further modified and brought out a little more detail. Adjusting saturation and luminance in opposite directions by a slight amount your image may be improved further. Note the minor differences in the hair color, shirt, tree trunk and more natural skin tones. Rarely should you have to reduce saturation below .80 or increase luminance beyond 1.10.

Tip: This is the time you may want to use the Brightness/Contrast filter. Usually you'll want to reduce brightness and increase contrast. If your image is still too dark you can either further adjust curves or increase Gamma. If your other adjustments were good, rarely would you want to adjust brightness or contrast by more than a few points in either direction. Remember doing so will change all pixels and effect what you already did with levels and curves.

We now have what most would consider a pretty well adjusted image. It is balanced with proper brightness levels revealing much more detail than the original did. We have good contrast and brightness with a major gain in detail. Now is the time to apply any needed color correction. By waiting until you adjust levels and curves you avoid having to adjust and perhaps over correct what appeared to be hue problems which frequently will resolve or become more obvious once levels and curves have been adjusted making any color balance adjustments easier and less extreme. While it isn't that much, there is still a slight red tint that should be removed, which we'll take care of next.

 

Image #5 after applying Levels, Color Curves, HSL and Color Balance. I reduced the red from the default 0.0000 to -0.0170 and also reduced the Blue to -0.0350. Note the effect on the shirt and especially the hair along with a slight warming up of the skin tone. To warm up images, especially where there are close up shots of people you'll want to use the Color Balance filter reducing Red and Blue. I generally reduce Blue first, then if needed, Red. Sometimes you'll get better results if you decrease Blue and increase Red, each slightly.

To cool off skin tones reverse the process increasing blue first, then increasing Red. Unless they are badly off you won't want to change the green hues very often if people are present in your scene. While you can, you'll spend lots of time readjusting the skin tones.

While not necessary, I finished by applying the Unsharpen mask as shown in the next image. How much or if you should even use any sharpening depends on the starting quality of your source files. With digital cameras the images should already be crisp. If you do add sharpening, remember a very small amount is all that is necessary. If you apply too much you'll make the edges of many pixels too obvious.The image below only had a very slight amount of sharpening applied and already you can begin to see it distorts the hair. So if you use any sharpening, remember a little goes a long way.

 

Image #6 after applying all filters. Note that the unsharp filter actually sharpens the image which is most visible in the tree bark, hair and eyes. I used the preset light which is a bit more than I would normally use. Sharpening videos in general isn't necessary unless you are working with some pretty bad source files. However sometimes just a little can improve your video a lot. In addition to the Unsharp filter there is a sharpen filter as well. OK, finished. As you can see just using just a few of the many included filters you can really improve less than pristine source files. Human nature being what it is the effect of applying the various filters often results in you wanting to tweak further what you did in previous steps. After sharpening, I increased luminance to 1.05, and brought back a little more contrast by pushing up Input start level to 0.030. I also decided a value of -0.0300 was better for blue. Experience and trial and error will tell you when you're starting to overdo it. Spending lots of time applying filters is just as bad as not applying any filters when your source files need some help. Strike a balance between not applying any filters and getting carried away.

Of course the best time to correct images is while the subject is still in front of the camera. Still you can still make real improvements post production. With a little practice it will become second nature. Even extensive use of filters doesn't take that long to do and the benefits are well worth the effort if you have less than pristine footage.

Image Washed Out

Original Image washed out. This is opposite problem of the first image that also can easily be corrected by applying levels and curves. This time the highlight and shadow regions have slopes in reverse direction and the shadow and upper midtone area is shifted further down near the upper portion of the shadow area. This type of "S" curve boosts the washed shadows the most and also helps out midtones more than highlights. A minor adjustment to tweak levels and do a simple color correction to warm up the image, redo levels a bit and we're well on our way to having a much improved video.

While most videos can be corrected by staying within the RGB channel you can make adjustments to the red, green and blue channels separately. This can be especially useful if you can't seem to get color balance right. Start by dropping the Color Balance filter on an event and work with the midtones, then move on to add a separate filter for shadows and/or highlights if needed. Future tutorials will show more advanced tips, but you should understand the basic correction methods explained in this tutorial first.

Tip: To adjust levels start with Gamma which can be found under the Levels filter. You rarely should have to go lower than .800 or higher than 1.200. If after adjusting Gamma and applying Color Curves you may wish to make slight adjustments by increasing the Input Start slider (under Levels) if you image is still a little washed out or by increasing Output Start to lighten the image further if it still seems a little bit on the dark side.

The "S" curve gets its name from its shape more obvious in this example than the other, however as you can see it is a flattened and sloped S shape. This one goes in the opposite direction than what we used to correct a image that was too dark. In the example it is dragged slightly down and to the right of center.

Additional control points can be added anywhere along the line to more precisely adjust just shadows, midtones on highlight areas. You can begin with a preset and adjust off of those if your prefer. You may wish to make several custom "S" curves to adjust for common conditions with each "S" a little different. While it takes some practice and some trial and error, this form of adjustment is far superior to using contrast and brightness by itself which effects the entire image a like amount. Using Color Curves combined with levels you get to pick which area of the image gets adjusted.