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Brightness and Contrast

Now that the image is masked, we want to dramatically increase the brightness in the tintype.  When I started using Picture Window, I used the Levels and color command, which would allow me to set the white point and the blackpoint, and adjust the midrange levels.  While this is reasonably simple and effective in many circumstances, using the power of the Brightness Curve command can be much more helpful.

The Brightness Curve command can be viewed in two ways, either as a curve, plotting the brightness of the original image against that of the output image, or as histograms of brightness in the original and output images.  Below is a screenshot of the Brightness Curve Command in use.

On the left is a closeup of the original photo (I removed the mask so you can see it clearly).  On the right is the output image from the Brightness Curve transformation.   In the center is the dialog box for the command.  You should note a few things on this dialog box.  In the upper left corner is the auto-preview box.  I almost always have this checked (for this command), so that I immediately see the results of my actions.  The input image is shown below this.  Immediately to the right of the amount slider is a copy of the mask I am using (white for the oval mask in the center, black where I have not masked the image).  The white and black pointers on the slider show how much the transformation is applied to the masked and unmasked parts of the image, respectively.   This curve is set to apply 100% to the masked area, and not at all to the unmasked area, so we are only operating on the tintype.

The top histogram is simply a count of all the pixels by brightness level, ranging from black (left) to white (right); the corresponding brightness level is shown immediately under the histogram.  As you can see, there is a large peak in the lighter gray region - this represents the photo album page.  Unfortunately, when you use this command with a mask you cannot limit the histogram to only the portion of the image covered by the mask (If anyone at Picture Window is reading...).  At the start, there is a corresponding histogram on the lower bar (representing the output image).  Our task is to insert control points on the original histogram, and re-adjust them for the output image so that the image looks more presentable.  Each of the arrow between the bars represents a control point.  They can be added by shift-clicking on the point of interest on the original brightness histogram, and then dragging the lower part of the arrow to the left or right, to make the original portion of the image lighter or darker.

How do we do this?  One more important tool in the dialog box is the image sampler, represented by the button with the eyedropper.  With this on, you can click on a portion of the original image, and find out where that area is on the histogram.   The way that I use this is to:

1) Click on an area of the image that I would like to see brighter or darker.   Usually, I start with the brightest portion of the image (in this case his shiny buckle, closely followed by his forehead), and find the area of the histogram represented. (The buckle is represented by the arrow to the left of the one pointing to pure white in the original image histogram - notice how much space there is between this and pure white).

2) Add a control point to this area of the histogram by shift-clicking on the point.

3)  Move the lower portion of the control point arrow to the desired brightness.   For the buckle and forehead, I brought it a few steps short of pure white, since they should be a little darker than pure white and to avoid losing all detail in those areas.

If I had just set this one control point, then many parts of the photo would become too light.  So I set another control point for an area just a bit darker than my first control point (the next control point to the left of the one for his buckle/forehead).   In this case, I used the shadowing in his cheeks, which I found by again using the sample probe tool.  In general, I've found it helpful to set one control point for the forehead (usually the brightest skin tone in this type of photo) and one for the cheek shadow.  By setting the output arrows for these to control points farther apart, you can usually increase the contrast in the face, and make a very flat facial picture look much more lifelike.

Once I set a control point for the cheek shadow, I increased the contrast between forehead and cheeks by increasing the distance between arrows for the output image as compared to the input image.  The farther the arrows are apart, the larger the portion of the greyscale range between the two points, and thus the more contrast between the points.

In addition to the above control points, I added one on the left side to bring the darker portions of the image to pure black, and one close to the right on the original image, which I brightened significantly so his uniform wouldn't be pure black and fade into the background.

The brightness curve command is a powerful command (and I believe the equivalent exists in all the major photo editing software packages).  As you can see, it can bring out detail in the photo that is hard to believe actually exists in the original.  It is worthwhile taking time to learn this command, and playing around with it using test images.

Using the brightness curve command, we get the following image.  Note that the album page is unaffected since we were only working on the masked area.

Looking at a closeup of the tintype:

you can now see some detail in the face and in the uniform.  Try as I might, I cannot bring out further details in the eyes.  This may in part be due to the long exposure times needed to take a tintype.  I've seen many where the eyes cannot be made out well due to the difficulty in holding still for long periods of time (this is why no one smiles in photographs from this era, it is too hard to hold it that long).  The long exposure times were especially a problem for photos of children, trying to get them to hold still for the necessary time.

Now he's brighter, but unfortunately he's a bright orange.  Next we'll work on color correction.


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