![]() ![]() In conclusion, we can do what Keynote '08 can do. ![]() The result is a tiger without background: I cleaned up the background with a few paintbruch strokes, adjusted brightness, contrast and threshold to make the tiger black, and then inverted this before putting it into the Alpha channel: With this tiger, I needed to convert a copy to grayscale first, Just for fun, here is another example obtained with a similar procedure: gif, it seems Seashore doesn't handle GIF transparency correctly. png, one of the common formats that support transparency. To verify this, the final result can now be exported as. If you set the Layers selector to display "All" again, the image should look pretty much like the original we started with, because the presence of the Alpha Channel is only noticeable if we now put the image onto a different background (the background color should shine through). Now we anchor the floating selection with our inverted image to the Alpha Channel:.So we simply invert the colors in this example, since our grid paper happens to be white: The image that will determine the transparency in the Alpha channel should be black wherever the picture is to be transparent.You could anchor it to the Alpha channel now, but we'll do that later. It will be in a "floating layer" for now. With the image copied to the clipboard, go to the Layers palette and set it to display only the Alpha Channel:.Choose Select all from the menu and copy the image.Make sure transparency (the "Alpha Channel") is enabled in your picture, as shown in the screenshot:.He tried to write like a computer here, which is fitting for this example. This isn't so easy because my son created it in pencil on grid paper, and since it's been scanned in the background isn't completely white. In Seashore, we want to make the background of the following image transparent: The manual procedure outlined here is just the bare minimum needed for creating a transparent background. Here are two approaches that work in Seashore: Seashore has lain dormant for a while but is still under development as of November 2010, with a user interface that is much simpler and more Mac-like than that of Gimp. This page was written at a time when there wasn't much easily accessible documentation for Seashore (there now is a user guide available for download at the project web site). On a separate page, I mention Seashore as a free bitmap drawing and manipulation program, based on the Gimp. Working with the Alpha Channel in Seashore ![]()
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