| 摘要 |
An image rendered by a non-alpha-channel-aware application is employed in an alpha-channel-aware environment. The pixel data file to be written to by the non- alpha-channel-aware application is initialized by setting the alpha value fo r each pixel to 1. The alpha-channel-aware application then writes to the initializ ed pixel data file, changing some or all pixel data. The alpha value for each pixel i s then decremented by 1 (modulo 256) making the changed pixels opaque and the unchanged pixels transparent.
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