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Losing transparency/opaqueness when saving to Jpeg


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I had a portion of an image transparent. When I saved the image to a jpeg, the transparent/opaque portion was flattened and as dark as the original....no transparency whatsoever.

I've been using The Gimp for the last few years. When I save to Jpeg, it warns that the Jpeg format does not translate transparency, then queries if I want to export the project prior to saving to Jpeg. When I do this, the final image comes out as I expect it to.

Does Paint.net have a similar export tool or setting that will allow the opaque setting of an image to carry over to a saved jpeg?

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I'm really not sure what you're saying here. JPG cannot save transparency, regardless of what program is saving it. (I too have been a GIMP user for the past few years.)

Now, I tested saving a black image as a .jpg with a semi-opaque area of black, and the semi-opaque area was just as black as the rest of it in the preview. If that is to what you're referring, the solution for the time being is to add a layer, move it to the bottom, and fill it with white.

If I'm not understanding your problem, perhaps you could post a screen shot of the image in PDN with the desired result before saving and the resultant JPG for comparison.

I am not a mechanism, I am part of the resistance;

I am an organism, an animal, a creature, I am a beast.

~ Becoming the Archetype

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Let me back up and explain a little better....

I've been working on sleeve for a CD in Inkscape, which is a freeware vector-based drawing tool. I am placing text on top of a graphic, so I have to make the graphic about 50% opaque so the text can be seen.

With inkscape, I can only save as a native file, or import to a bitmap. When I import to a bitmap and open the file, the graphic remains light, and the text is still readable.

Now, when I open the bitmap in The Gimp and save as a jpeg, I get the same result as above. When I open the bitmap in Paint.net and save as a jpeg, the graphic returns to it's original state (i.e. darker), and the text cannot be read.

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I am exporting the file from inkscape as a .png (ping) bitmap, then opening it directly with Paint.net. When I export from paint to a jpeg, the image that was originally lightened in inkscape (via opaque setting) is converted back to it's original state.

When I do the same sequence using Gimp instead of Paint, it works fine. The only difference is that Gimp warns the transparency will be lost because jpeg cannot translate it. Gimp offers to export the file first, to which I choose "yes". The resulting jpeg comes out fine.

BTW - Inkscape only exports to .png. Otherwise I would export directly to jpeg and skip the Gimp or Paint conversion.

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Ah, I see. I have been able to recreate this behavior.

Since JPG doesn't save transparency, I suppose there's no real standard as to how the final output should look when you start with no fully opaque layers. With PDN, since there's no other layer with 255 alpha with which to blend the translucent layer, it sets the alpha of the translucent layer to 255. The GIMP seems to blend the alpha as if there where a solid white layer behind it.

If you add a layer behind the graphic and fill it with white, you should get the result you're looking for.

I hope that helps,

Dan

I am not a mechanism, I am part of the resistance;

I am an organism, an animal, a creature, I am a beast.

~ Becoming the Archetype

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