2007 SLP Curriculum Guide #04, Photo Brighteners
Brightening photographs often is one of the main enhancements needed. We have covered the Auto Fixes and both Brighten/Contrast and Curves. In this guide we will cover a number of other brightening features that also can be used to fix photographs (Gamma Correction, Histogram, and Levels). In this illustration I am using a photograph of myself which is both dark and has a purple cast to it.
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The illustration table will show how different features work on this current photograph. Notice how each of these features produce a similar result. The end result in some cases is not how I would ultimately finish the photograph as some additional corrections would be needed particularly in using a color enhancer which we will cover in another guide.
For those of you a bit more interested in the technical aspects of these features the following are some comments.
- Colors are actually made up of Hue (the color value), Saturation (the amount of color intensity), and Lightness (bright/dark values). When using the Material Palette in addition to the Red, Green, Blue values one can work with the Hue, Saturation, Lightness or HSL values.
- Though not necessary to working with photographs, one could spend some time playing with these values. And, by comparing the RGB and HSL values one can get a better idea of how to set and/or mix colors. Also, when one sets the RGB value to a color then one can see the HSL values that correspond to that color. Finally, as one varies the HSL values watch the palette color wheel to see how the two circles move to find that color on the color wheel.
- If you want to learn the color coding for use in web pages then watch the HTML value box. The first two (letters or numbers) are the Red values, the second two are the Green ones and the third set are the Blue values. The basic advantage of knowing how to set the Hexadecimal values and how color hues are mixed to create the range of colors is that in some instances one then can more accurately and quickly use the various PSP features. However, just playing with the feature option values will also work well.
Auto Fix Default
Color Balance: Checked
Auto Fix Enhanced
Color Balance: checked and picture (upper right) and right side of beard checked.
Using version 10 Smart Photo at Default Levels the Original Picture is lightened yet still has a purple cast to it. However, adjusting some of the options, I was able to achieve a better color balanced photograph. The enhanced photograph might be a tad dark but further changes would involve another PSP feature whether Brightness/Contrast or perhaps Curves.
Gamma Correction is a feature that allows both brightening and some ability to fix colors in a photograph. In Version 10, 'Gamma Correction' is hidden so one first has to make its tool bar icon visible. Check out Guide #09 of the 2006 - 2007 listing and the two tutorials referenced for customizing workspaces.
Gamma Correction works by altering the Red, Green and Blue channels of a photograph and thus can both brighten and to some extent fix color balance. When the Gamma Correction window is visible there is a check box LINK that will automatically link the RGB values so that one can change them just by dragging one of the switches. When the LINK box is unchecked one can drag each color channel individually.
Take a little time to just work with the switches. One tip is that by clicking on the switches and then using the arrows will also move the switch. Also after unchecking the LINK box and setting the R, G, B values one can again check the LINK box and then again work with the overall brightness.
The illustration uses the values of R = 1.90, G = 1.50 and B = 1.20. Although the Gamma Correction works nicely alone, I tend to use other features to refine the result.
The Histogram Adjustment feature is a most interesting feature in that it has a number of options which are able to be varied to produce an enhanced result. The general options available are to EDIT Luminance and/or Colors.
Working each of these separately starting with Luminance will ultimately get one to an enhanced photograph.
- The Midtones Compress switch (-20) tends to decrease/increase Contrast.
- The Output (Max (255)/Min(20)) switches will increase/decrease Brightness. Lowering max output darkens and increasing min output brightens.
- The Gamma (low (0), gamma (1.40) to high (255) values which also govern the arrows at the bottom of the display) both increase/decrease brightness and contrast.
- Experiment with these Luminance values to find a brightness fix that you like. There may, as in my case, still be a color fix needed as my brightened photograph still had a purple cast to it at the values I selected.
- When satisfied with the luminance values, click on OK to set it.
Next, as in my illustration, the purple cast still existed so I set Edit to Colors. If you have some understanding of how the Red, Green, and Blue values work together to create colors you can begin by determining what color value you want to start with. For instance, Red/Blue together creates purple while Red/Green together create Yellow and Green/Blue create Cyan.
To gain an understanding of using the Edit/Color and the respective color values, just play with the various options. In the illustration I first set color to Blue and then set the Gamma value to .70 which did remove for the most part the purple cast. Then I worked with the Midtones compression and set it to 10 initially which removed more of the purple cast. I then set the Output minimum to 40 which brightened the picture more but returned a bit of purple. So, I increased Midtones Compression to 20. When satisfied set it by clicking on OK.
In working the Histogram Adjustment feature work the changes of values in small increments. However when first learning to use this feature, exaggerate the values and combination of values to see how each option works. Also, you may want to return to the Luminance edit setting, return the values present to their default values (click on the default arrow) and then readjust luminance. I did that for the illustration by setting the luminance gamma value to .90 which darkened the photograph just a tad.
The 'Levels' feature is another one that works with the Hue values to correct or fix photographs. This feature uses a window that allows one to work the channels (RGB, or Red, Green, Blue individually). One varies the Input and output values for the particular channel. by dragging the right or left slide. As with other features just experiment with the settings and values to see how this feature works.
Also, keep in mind that very accurate option values can be achieved by first clicking on the option setting (slide) and then using the up or down arrows on the keyboard. And, again unless one is very technical the way to obtain a decent fix is the visual or seeing what one likes for a final result. Thus, when satisfied just click on the OK button to set the fix.
The values I used in the illustration are: RGB (Input of 0,1,155 and Output of 0,255), Red (default values), Green (Input of 0,1,255 and Output of 0,244), Blue (Input of 0,1,255 and Output of 0,180).
There are a couple of other PSP Brightness/Contrast features such as Threshold and Highlight/Midtone/Shadows and Clarify. I have yet to find a way to effectively use Threshold. However, Highlight/Midtone/Shadows particularly when the Relative Adjustment Method is activated can be used to nicely fix brightness and shows. Clarify is a very neat feature I often use at the end of my fixing process as it subtly affects the sharpness of the finished product by automatically fixing shadow/brightness values.
These Brightness/Contrast features all do much the same thing as said above. Yet learning them one can often use one or another to refine a photographic fix. Again, as often said just experiment, try things out and you will learn which features you like best and how to use them to your advantage in enhancing photographs.
In the next guide we will explore features that work on the colors of photographs.
- When completing a tutorial or series of tutorials, and having placed them upon your web page, post in the SLP Forum your completed work using this layout:
- Name or Screen Name.
- Web Site URL.
- Version of PSP using.
- List of Tutorials completed.
- Post your Work:
- List what you did, feature, options used, values.
- Indicate steps taken and results.
- Indicate things you found interesting, worthwhile and any other comments.
- List some of the similarities you found between the Menu System, Palettes, and Keyboard shortcuts.
- Post any questions and comments in the SLP Forum.
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