Difference between Import and Format plugin types for Photoshop

My task is to work on a Photoshop plugin to read an oddball image file format. Should I write an "Import" or a "Format" type plugin? What is the difference? I've read Adobe's docs, but am not seeing the key point (and am quite new to开发者_JS百科 Photoshop plugin programming)

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Just going on what CS2 installs The only plug-in that lives in my Photoshop import/export plugin directory is the twain_32.8BA (for scanning images). All the .8BI files in the file formats directory are for bmp, tga, pcx etc. So by that alone I suggest you write a file format plugin for a new oddball image format.

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Format plugin allow you to add file format as native, so you will be able to save and open files as usual (from save, open or by double clicking on file).

Import plugin is somewhat more special, you will use File->Import. Also Import plugin can not save images.

So if you need to work with your format as just with any other format use Format plugin. If you want your format to be somewhat not native, foreign to photoshop use Import type.