How to Mask a Digital Image

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By Richard Burke
eHow Contributing Writer

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Original Image

A distinct advantage of Digital Photography is to be able to manipulate the image in post production. Most manipulations are simple in nature, like cropping the image or adjusting the contrast or brightness. There may be times that editing the image requires more complicated procedures; you may want to create a mask for an image to allow you to adjust color or brightness for only part of an image—or you may want to create an image mask to use with a page makeup program to adjust the image for printing. Some artists use masking to create basic shapes that will then be used with illustration software to create original art. This article will explore the basics of the Quick Mask feature of GIMP Image Editing software. Adobe Photoshop also has masking features, as do many other image editing programs.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

GIMP Image Editing Software
A copy of an image for experimentation
Patience
Practice

Step 1

Fuzzy Select

Open the image and use the FUZZY SELECT tool or LASSO tool to select the part of the image that you want to leave “unmasked." Remember with the FUZZY SELECT to use SHIFT and CLICK to add to the selection. Here we used the fuzzy select tool since the background is very complex; with a plain background the lasso tool may work better. Remember to ZOOM IN on the image to make selection easier regardless of the tool used.
Step 2

QuickMask

The mask will cover the entire image except for the area selected. In the old days of printing, ruby colored polyester material was used to mask images while burning printing plates. Windows were cut into the masks to allow the photographic images to be burned onto plate and to prevent the text from being burned in. Masks were also used to make borders around images. Digital masks work in the same way, and as you can see, the only unmasked part of the image is what we selected. The same ruby color is used, as with the old analog method. Toggle the mask on and off using SHIFT+Q or select TOGGLE QUICKMASK from the SELECT menu.
Step 3

Create New Image

To create a mask, select NEW from the FILE menu and create a new file with a white or transparent background. From the masked original, select copy and paste it into the new file. Save the file and you have created a MASK of the original.
Step 4

Image Mask

This new image can be used as a printing mask or can be used as an original art file in a program like Adobe Illustrator to create an original illustration. You can invert the properties, duplicate it, create a new layer with it, colorize it or use it in a variety of special effects.
Step 5

Change Color

You can also use the mask with the original to change the color or any other image property. Masking allows you to be creative with a part of an image. When you use masking in combination with other selection tools you can dramatically alter the properties of any image or use part of any image in an original creation. It is not easy, but is worth the effort to allow the photographer to have complete control over image reproduction.

Comments

dsarokin said

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on 8/8/2008 OMG this is so cool. I used to do manual masking back in my darkroom days, but I didn't really know how it translated to digital photos. Thanks for a great article.