Reductions and Selections in Photoshop | Subject: Reductions and Selections in Photoshop by BikerBot on 2004/7/24 12:50:46
The Lords and Ladies of Heromorph have requested that I post some of my tips for proper Selection and Reduction in Photoshop. Enjoy:
Clean up selections using the Smooth command in Photoshop
If you use the Magic Wand tool for making selections or have to expand or contract a selection, you'll find that the selection is a bit messy. To clean it up choose Select > Modify > Smooth and enter a radius value equal to the amount that that you expanded or contracted your selection by or try a radius between 2 and 6.
Avoid jagged lines when making selections in Photoshop
Many times when making quick selections using the Magic Wand tool or the Lasso tool the final outcome isn't as crisp as we'd like it to be. To fix this, after making a selection enter into Quick Mask Mode by pressing Q on the keyboard. Then, choose Filter > Noise > Median. In the resulting dialog box, increase the Radius until your selection is smooth. Then click OK. After smoothing out your selection, return to Standard Mode by pressing Q again. That's all there is to it!
A quick fix for jagged line art in Photoshop
Cleaning up messy line art can be a breeze. More than likely, if it's line art, then the image was saved as a bitmap. Open the image in Photoshop and convert it to Grayscale by selecting Image > Mode > Grayscale. Keep the Size Ratio as 1 and click OK. Then choose Filter > Blur > Gaussian Blur and apply a slight blur that removes all the uneven edges. Usually this is a Radius between 1 and 5 pixels. Then click OK. Next, choose Image > Adjust > Threshold and adjust the slider so your image is only black and white. Finally, convert your image back into a bitmap, by selecting Image > Mode > Bitmap. In the Bitmap dialog box, set the Resolution Output to 600 ppi and choose 50% Threshold as the Method.
Erasing the background of an image in Photoshop
Photoshop's Background Eraser tool is the perfect tool to use to eliminate any unnecessary background scenery, while preserving the foreground information. To test it out, open an image in Photoshop and select the Background Eraser tool. Then click on an area that you want to erase within your image. The trick when using this tool is to make sure that the cross in the center of your brush is only touching the pixels that make up the background of your image. If you accidentally touch part of the foreground with this cross, the Background Eraser tool then erases the foreground as well.
Keeping reductions sharp in Photoshop
Have you've discovered images from your digital camera look muddy after resizing them to make their size more manageable for the Web. The most probable reason for the image's appearance is the manner in which you're reducing the images. Most of the time, when you resize an image in Photoshop, you're using the bicubic algorithm, and therein lies the problem. As it resizes the image, it averages the color areas of the corresponding areas to determine the color value for each pixel in the new image. While minimal reductions don't do much, big changes in the size of an image can make the resulting image appear a bit soft (or muddy, if you must). So much so that the Unsharp Mask trick doesn't work. The solution isn't to throw out the bicubic reduction, but rather to go about things a little more slowly.
For example, if you're reducing a large digital image of 1536 by 2048 pixels to something like 154 by 205 pixels (a reduction to 10 percent), you should go about it in steps. First, reduce it by 50 percent and then use the Unsharp Mask filter (with a 50-percent Amount, a 1-pixel Radius and a 0 Threshold).
Now, reduce the image again by 50 percent and then reapply the Unsharp Mask filter. Finally, reduce the image to the final size and reapply the filter. By doing the reduction in steps, and by correcting the image as you go along, the resulting images will be much cleaner.
After reviewing how well this technique works, you might even consider creating an action in Photoshop to do the reduction and correction automatically. That way, you not only save time but get better results as well.
Safe settings for Photoshop's Unsharp Mask filter
The Unsharp Mask filter, contrary to its name, sharpens and adds contrast to images. Knowing what settings to plug in for this filter can be a bit perplexing. So, rather than just arbitrarily guessing what numbers to put in for the Amount, Radius and Threshold try the following settings. For images that are already sharp and hold a lot of detail, set the Amount to 70%, the Radius to 4 pixels and Threshold to 3 pixels. For soft or slightly blurred images set the Amount to 180%, the Radius to 2 pixels and the Threshold to 6 pixels. From there you can make slight adjustments for maximum quality. And remember that it's good practice to over sharpen the image a bit (just a bit) because it will be softened when it's printed.
Avoid unwanted halos when sharpening images in Photoshop
When you apply the Unsharp Mask filter to a color image, the filter automatically adjusts each color channel causing unwanted halos around the edges of your image. To keep this from happening, convert your image to Lab mode by choosing Image > Mode > Lab Color. Then apply the Unsharp Mask to the Lightness layer only in the Channels palette. This will bring out the detail without affecting the colors of your image.
BikerBot
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