Adobe Photoshop Tutorial. Copyright Michael B. Karbo.

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    19. Introduction to masks

    In this and the following chapter you will work with Layer masks, which is an important tool in Photoshop.

    You see that the masks can mix different picture layers. Here comes four quite different exercises. Together they illustrate a small segment af the lage leeway, which the layer masks can give the creative picture processor.

    What is a mask?

    A mask is a special ”layer”, which you can place over a picture. The mask acts like a selection; it divides the picture in different areas. When the picture is masked, it can consist of three types of areas:

    ·     Areas that are hidden and thus masked against changes. Those areas are shown with black in the mask.

    ·     Areas that are visible and which can be changed. That is like a selection. These are shown with white in the mask.

    ·     Areas which can be partially changed. These areas are shown with gray tones. The lighter a masked area is, the stronger the change will be.

    The protected areas will remain unchanged, regardless of whatever else you use the mask for. But the unprotected areas can be treated in many different ways. The areas can be completely or partially transparent, so picture data from the underlying layers can ”look through”; that is called a layer mask.

    The special feature about masks is that they in themselves can be treated with filters and other tools. In that way the masks provide very broad room for creative picture processing. You can use all thee effects you desire, without having to change the actual picture data.

    Figure 40. A mask, which has the shape of a wine glass.

    Masks are a rather difficult subject – especially when its has to be explained! We can get in doubt ourselves – why is the mask black and not white there? Those kinds of questions can rumble around in your head if you try to understand it all. Therefore, our suggestion is: Try for yoourself to works with masks, do the exercises in this chapter. Then you will discover that masks are excellent tools, which actually are easy to use in daily work!

    Make the first mask

    Now you are going to see how a mask works. Follow this exercise, where we blend two pictures by using a layer mask.

    1.   Open the image file calme.jpg, which you can get from the home page for this booklet.

    2.   Doubleclick in the Background layer beam:


    3.   Click on OK, so the layer is ”unlocked” and renamed to Layer 0.

    4.   Now you have to insert a layer mask. Select menu items Layer --> Add Layer mask --> Hide All:

    5.   The picture disappears! There are two possibilities when you insert a new layer mask. The mask is either white or black. This mask is black, and with that it hides all picture data. You can see the mask in the layers palette:

    6.   Try to click alternately on the mask (the thumbnail) as seen above, and on the picture itself. It is hard to see if anything happens in the layer beam, but it works: The picture and mask get alternately active for editing.

    Figure 41. The Layer mask is seen as a miniature image to the right of the picture thumbnail. Either the mask or the picture is active for editing.

    Work in the mask

    You have a picture that right now is completely coevered by a (black) mask. Let us work on the mask.

    1.   The picture looks empty; you see the chckered background, which indicates that there are no pixels here. Click in the mask miniature to activate it.

    2.   Select the brush tool (press b). Choose a soft brush in size 100 pixels.

    3.   Choose the default colors (press d) – here it will be white/black, siince the colors are reversed in a mask compared to the normal.

    4.   Paint some brush strokes in the empty picture surface. The picture appears! Why? Because you (as usual) paint with the foreground color, which here is white. The mask’s black areas are hidden. But where you paint with white, the areas become visible:

    5.   So the white brush breaks a ”hole” in the mask. You can also see that in the layer mask’s thumbnail in the layer beam:

    6.   Paint a little more, and notice the effect both in the picture and in the mask thumbnail.

    7.   You can always de-activate the mask by clicking on the mask thumbnail while you hold the Shift- key down. Try that:


    8.   The mask is re-activeted with a simple click in the thumbnail. Do that. Try to reverse the two colors (press x). Now paint with black – so you can close the mask, so it covers the whole picture. Can you see the system?

    9.   Try to choose a gray color and paint with that. It might be a little difficult to see, but it results in partial tansparency in the mask when you paint with that.

    10. Finally paint with black, so the whole mask is closed (and you cannot see any picture). Save the picture as calme.psd, and leave the image file open in Photoshop.

    Look through the layer mask

    Now you will continue working with the mask. You do that by inserting a new picture, which will be blended into the existing.

    1.   Open the image file jaguar.jpg in Photoshop. Make copy of the picture with Control+a and Control+c.

    2.   Switch to the image file calme.psd, and insert the copy there (Control+Tab and Control+v).

    3.   Now you have two pictures each on their own layer in the same image file. Drag the new layer (Layer 1) down below Layer 0. Rename the two layers to calme and jaguar, like here:

    4.   It is still the car that is seen, since the black mask hides all picture data from the calme layer. But we can change that easily. Select the mask (but not the picture!) in the calme layer:

    5.   Choose the default colors (press d), and fill the whole mask with the foreground color white (press Alt+Backspace). The mask will be colored white:


    6.   This means that all the layer’s picture data are seen now, and therefore the car is no longer seen. Now select the brush tool (press b). Choose a soft brush in size 100.

    7.   Reverse fore- and background colors by pressing x. Now paint in the mask. Because you paint with black, you get to look down to the underlying layer:

    8.   Use the brush to make the whole car visible. Try to reverse the two colors again (press x) and paint with white. Then you can cover the car. You will need to reverse fore- and background colors repeatedly.

    9.   When the whole car becomes visible, you need to reduce the brush’s opacity to 50%:

    10. With white as foreground color you can now cover part of the car with a thin ”water layer”, so it looks as if the car is on its way out of the sea.

    11. Save the image file.

    Figure 42. The mask makes the car come only partly out of the water.

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