background elimination : Java Glossary


background elimination
GIF flower without variable transparency
GIF flower without variable transparency
PNG flower with variable transparency
PNG flower with variable transparency

How do you create images that with transparent backgrounds that appear to float on any colour of background? This is nearly always done with a png file with a variable transparency. Note the featherly looking flower on the right. The flower to its right, with the grainy spikes, is done without variable transparency, gif-style. It can be quite a bit of work to eliminate the background. Here are some of the techniques I use:

Compact way

Products are often displayed with a jpg on a pure white background. So long as you show them on a pure white background the background will appear to be transparent. The jpg images are much more compact that a true transparent background png image would be. That is why this technique is so popular on commercial sites. You can also replace the white with the colour of your particular background. You can also change your background to match the background of the image, a trick I use for the image of the day on my home page.

Easy Images

If the image already has a background with a solid colour, there is very little work you have to do. You can use a tool like PSP palette to select that background colour as the transparency colour. This works so long as there is none of that background colour in the foreground. If there is, you must touch it up with a non-transparent version of the background colour. You can also use the flood fill tool in Icon Lover to flood the background with the transparency colour. It won’t leak through to islands of the background colour in the foreground. You can use PSP background eraser tool to touch up the edges. You simply get it near the edge and it finds the precise edge. However, if the contrast is not high enough it overshoots the edge and floods the foreground image. Just do a little at a time and pause so that when you use undo, you won’t wipe out a huge amount of work. Using the PSP background eraser as your only tool is quite tedious.

Busy Images

If the background is complex, use the free Picture Cutout Guide Lite utility (or its for pay big brother Picture Cutout Guide ). With it, you either roughly mark the boundary between foreground and background or roughly mark what counts as foreground and what as background and it finds the precise edge and cuts the image out. It will not apply a transparent background directly, but it will apply a white one. (You can in the full version.) Use Icon Lover replace colour tool to replace the white background with a transparent one. Touch up in Icon Lover with the background eraser tool. For stray bits of background in the foreground, use the clone tool in PSP to touch them up with bits of nearby background. You can of course use Picture Cutout Guide on easy images too. The main problem with Picture Cutout Guide is it tends to leave a thin dark line around the foreground image and jaggy lines when you work on small images.

thin dark line
thin dark line
jaggy lines
jaggy lines

It also lets you instantly cut out objects, move them around and fake in backgrounds that were previously obscured. You can make people disappear from a picture or move them into a totally different scene.

General Tips

Work on the biggest original you can find. When you have it all clean, then crop it and resize it using PSP (which lets you preview the size) or Icon Lover which does the best job of anti-aliasing and blending of transparent and non-transparent regions of the transparency. Shrinking hides any flaws in your detail work.

Better Tools

I am still on the lookout for still better quality tools. I have tried a number. All have proved inept. Obviously magazines and commercial websites have ways of doing this that get much better results than I can.

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