Adobe Photoshop Tutorial. Copyright Michael B. Karbo.
24. Repairs (1. step)
Now we will cover repairing pictures. If you have a digital camera, you will also need Photoshop. Here is a couple of small exercises, where we will improve pictures with:
· Improved sharpness
· Correction for wide angle exposures
· Correction for ”red eye”
Those are tips, which you often can use.
Even though a picture may appear sharp, you can sometimes improve it with additional sharpness. Let us try.
1. Get the picture victor.jpg from the home page for this booklet, and read it into Photoshop. That is a picture of an ancient church in Marseille (St. Victor).
2. Try to zoom in on the brickwork. Is it sharp? That is hard to tell; the picture is saved with high compression in JPG format, and that automatically causes some blurring and unsharp areas.
3. Select menu items Filter --> Sharpen --> Unsharp Mask … This very flexible filter can improve the sharpness of the picture:
4. That opens a small dialog box with three settings fields. Try to experiment with them. You can follow the filter’s effect both in the dialog box’s small image window and in the large picture. Try to turn Preview on and off, then it is easy to see the effect.
5. Our attempt showed that an amount of around 44% was suitable. Radius landed near 3,9 pixels. The threshold level needs to be kept low (2), otherwise only very few pixels are sharpened.
6. Don’t overdo the sharpness, or the picture can soon get ugly. When you find the right setting, click on OK.
7. Save the picture again (in the JPG format).
The wide angle lens
You have proably noticed that the picture is tilted. I had to use a wide angle lens to catch the whole building in the picture. And that gives geometrical distortions; the horizontal and vertical lines in the figure are slanted.
Figure 59. Here the photographer was not drunk from pastis; the picture was taken from a short distance away and with a wide angle lens. That caused an obvious distortion in the left side of the picture.
Let us try to correct the geometry of the picture. First Select all with Control+a.
Then choose Edit --> Transform --> Distort:
2. Now the picture gets equipped with black handles in each corner. It is easiest to adjust the picture if it is relatively small compared to the window size, as shown below (zoom out once or twice with Control+-). You might have to drag in the window edges to enlarge the window:
3. You need to drag the left two picture corners away from the picture center to restore the geometry. Try something like this:
4. The transformation is finished by pressing Enter. Then the proportions are in place.
5. You might need the clone tool to fill empty picture areas after the transformation.
6. Save the picture again.
The Transformation function exists in different variations, which can be used for quite different tasks. Below you se the result of a small operation, which can be done in very short time:
Figure 60. The Transformation function can save tilted pictures.
Try for yourself
Earlier in this booklet (page 67) you used the function ”Free transform”, which is a very flexible tool. Just try this:
1. Get the picture eiffel1.jpg, and read it into Photoshop. The photograph shows a soccer field seen from the top of the Eiffel tower in Paris.
2. Zoom out a couple of times with Control+- (minus), to get room around the picture area. Select all with Control+a.
3. Select Free transform with Control+t.
4. Hold the Control key down. Drag in the black handles using the mouse curor. Now you can distort thee picture’s proportions, as you did in the preceding exercise.
5. Try drag in the handles to make the soccer field rectangular.
6. The picture will be used later in the booklet, so don’t make any other changes in it. Select File --> Save as, and save the corrected picture version as eiffel1c.jpg.
In flash photography you might encounter portraits with ”red eyes”. It does not happen with all cameras, but if you run into that problem, it is quite easy to work around the problem.
1. Get the image file redeye.jpg from the home page for this booklet, and read it into Photoshop.
2. The picture shows a typical example of ”red eyes” caused by flash photography:
3. The red pupil needs to be corrected. Insert a new layer in the picture (use Control+Shift-+n).
4. Select an elliptical selection frame from the tool box. Set feathering to 5 px in the settings line, and make a circle around the pupil:
5. Then choose the color adjustment Image --> Adjustments --> Hue/Saturation. You can also press Control+u to activate the function.
6. Now you just need to adjust the red color – it needs to be completely obliterated. First select the Reds channel in the Edit field:
7. Then drag the slider by Lightness all the way to the left:
8. Click on OK. That solves the problem. Save the image file as redeye2.jpg.