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Working with Corel PhotoPaint’s Contrast Enhancement

One of the problems that you may face when you are doing photographs is that your photos may be to “dark” or maybe to “light”. Figure 1 shows a photo that falls into the category of being to “dark”. If you look at the photo you will notice that the highlights (the cupboards are “grayish” not white) are not white but gray. This is a tell tale sign that the image lacks the proper information in the highlight areas. This lack of information is shown as a photo that is to dark or has a colour cast. Although there maybe other issues with the image, this exercise will concentrate on quickly correcting contrast issues that can happen when you are giving a photograph. Sometimes the results achieved by a few mouse clicks can greatly enhance an image. So let us get started.

Here is our Photo


1. As we can see from Figure 1 our image is to dark. If we look closely at the white areas of the photos you will notice that they tend to be gray – not the white that they should be. The white areas we classify as the highlight area of our photo. Our shadow areas – the dark areas seem to be all right. Thus we need to concentrate on the highlight areas not the shadow areas. This photo has nice colours but it just needs to have the exposure lightened up.
2. Although there are a number of tools available for us to use to correct the image I will concentrate on using the contrast enhancement tool to help achieve better results for this photo. Note: For earlier versions of Corel PhotoPaint this tool is called the levels command. In Photoshop this is called the levels command.
3. So let us open up the image in PhotoPaint.
4. Now some of you that are familiar with this tool may be tempted to go to “image” “adjust” and select the tool. I would suggest that instead of opening the tool this way that we use the tool but we place it on a lens. What is a lens? A lens (in Photoshop this is an adjustment layer) is a layer that is separate from the actual image. What this means is that you can apply the effect/tool to your image and but it does not effect the original image. The lens sits on top of the original image and the tool/effect can be seen. If you want to adjust the tool or delete it you can work on the lens without affecting the original image. This is a very important technique that you need to master when you are working in PhotoPaint.

Open the Objects Dockers


First go to “Window” “Docker” “Objects” and select objects. See Figure 2.

Our Object Window is Docked


Figure 3 shows you the docker window that becomes active in PhotoPaint.

Lens Icon


For now the only thing that is important is the “eye” image which allows you to “hide” each layer is active. The layer/object is called “the background”.
Now if you look to the bottom of the object docker you will see a number of icons. Each of these icons activates a different function. The one we want to click on is the one marked by the red box in Figure 4. This activates the lens command.

Select The Level Equalization Lens


Figure 5 shows the command window that comes up when you select the lens command. If you are in Corel 9 or less, select the levels equalization or for newer versions choose the contrast enhancement. Click “Okay”. You be presented with a new dialogue box.
Note: Corel’s definition for the level equalization is as follows – The Level Equalization filter lets you change shadow, midtone, and highlighted areas by redistributing shades from darkest to lightest. Level equalization lets you preserve shadow and highlight detail that is lost when you adjust the brightness, contrast, and intensity of the tone of an image. You can also use the Level Equalization filter to create color gradations on posterized images; to lighten or darken any combination of shadows, midtones, or highlights; to compress brightness values to printable limits; and to adjust the gamma curve (midtones).

Adjust Your Settings


Figure 6 shows the dialogue box that comes up. Although there are a number of controls in this dialogue box there are some that are more important than others. Let us review some of the most important controls.
Shadow Input Slider – Red Box – the red box allows us to darken the image. In essence, what has happened is that we have closed up the tonal range of the image towards the shadow area.
Highlite Input Slider – Blue Box – the blue box does the opposite of the red box. It lightens the image and shifts the tonal range of the image towards the highlights.
Gamma Adjustment – is the adjustment for the midtones in the image.
Auto Adjust – Purple Box – is the “Auto Adjustment”. This switch allows us to have Corel automatically adjust the image for us.
So let us try a couple of things If we look at a “good quality photo (one with good shadows, midtones and highlights we tend to see a histogram that is well distributed across the tonal range. Figure 7 shows a histogram that has better distribution of values over the full tonal range. Note: This is not always the case though, so care needs to be taken. Some images lack shadows or highlights and thus the histogram can be skewed to one side or the other. Later, when our test image is fixed you will see a histogram that is well distributed or like Figure 7.


Method 1 – Auto Adjustment


I will review 3 methods that you can use to attempt to correct the attached photo. The first method is the easiest of the three. All you need to do is click on the auto adjust button (purple button in figure 7 and the image will be corrected. Figure 6.
A new lens or object/layer is created which is visible in the object window.

Method 1 Adjustment


You will have the contrast enhancement / levels dialogue box come up.
Select the “auto adjust” as per figure 6 – Purple box.
Make sure that the “preview” button is depressed.
Click okay. A new object is created in the Objects docker window. If you want to see what the original image looks like you can just click on the eye icon to the left of the object.
The image will automatically adjust for you. Figure 8 shows you the corrected image.12. You will have the contrast enhancement / levels dialogue box come up.
Select the “auto adjust” as per figure 6 – Purple box.
Make sure that the “preview” button is depressed.
Click okay. A new object is created in the Objects docker window. If you want to see what the original image looks like you can just click on the eye icon to the left of the object.
The image will automatically adjust for you. Figure 8 shows you the corrected image.
The problem with this technique is that the image has a blue cast in it. This is better, but is still not good. Note in Corel 11 the auto adjusts worked a lot better.

Method 2 – Adjust the RGB values altogether.


One of the techniques that you can use is to select the upper right slider in the contrast box – blue box in Figure 6. Pull the slider over till it lines up with the first hill. You will notice that the histogram starts to spread out to the right, which means that you are expanding the tonal range of the image.
Figure 10 shows a red line which is where you need to pull the slider to. This adjusts all the RGB values at once.

Here is Our Finished Image


20. Figure 11 shows the corrected image. You will notice that the image is getting better.
21. I like using this technique if I am working with a grayscale image. This is a quick way of improving the image with little work.
22. Figure 11 shows the finished image

Method 3 – Adjusting the image via the 3 RGB Channels


23. Another way to correct the image would be to adjust the 3 channels separately.
24. In the “Channel” section of the contrast enhancement dialogue box select the red channel see Figure 12.

Adjust the Red


25. We will not adjust each channel separately
26. Next pull the slider along till it touches the edge of the first mound (blue line). See figure 1

Adjust the Green


27. Repeat for the green channel – see Figure 14. Make sure that you select the pull down bar and change from the “red” channel to the “green” channel.

Adjust the Blue


28. Repeat for the Blue Channel – see Figure 15

Here is Our Finished Image


29. Figure 16 shows you the finished image.

Our Image Now has no Colour Cast

31. If you want to lighten up the image even further you could create another contrast enhancement lens and place it on top of the original.
Well, there you have it. We have “fixed” our image in a matter of minutes. What have we done you may ask? What we have done is increase the tonal range of the image by shifting more pixels to the lighter side of the RGB spectrum. This has greatly enhanced our image and has turned this dark image into a lighter, more colorful image that will look great on one of our sublimatible products.


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