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transparency differences between jitter and photoshop

June 6, 2011 | 10:20 am

Hi all,
This could very well be highlighting the fact that when it comes to photoshop, I really don't know what I'm doing, but maybe I'll get lucky! I have some text in photoshop with a bit of drop shadow. There's a bit of blending at the edge fading from an opacity of 100 to opacity of 0. The two images attached show what photoshop renders and what jitter renders. Basically anywhere the opacity is < 100, the region appears as light grey in jitter. So the question is...how do I get these to look the same (preferably jitter looking like photoshop).

my usual method is "importmovie" >> jit.matrix >> jit.gl.videoplane

mac os 10.6.7. latest version of max.

Thanks in advance for any advice.

David

[attachment=163788,2332] [attachment=163788,2333]

Attachments:
  1. photoshop.jpg

July 6, 2011 | 1:17 am

can you post your patch and the file that you are importing? I can’t recreate your error. I used the jit.qt.movie instead of starting out with a matrix.

It could have something to do with the file that you are using. jpgs don’t hold transparency, so when you are saving the image photoshop will automatically flatten the image. Try flattening in photoshop before saving the jpg. You can do this under layer on the menubar.

You could also experiment with different filetypes. tiff handles transparency better than jpg. Gif will hold transparency, but i can’t remember if qt like gif or not.

Is the background going to stay the same or change?


July 6, 2011 | 7:29 pm

if you want the alpha channel, go with .png every time. if you don’t want it, flatten it first with photoshop and export as .jpg. remember that you will need jit.alphablend to visualize the alpha channel if you’re not going into GPU.


July 6, 2011 | 7:49 pm

I use png all the time when I need to preserve transparency.
the issue I reported above seemed to have been related to something else.
Cheers,
David


July 7, 2011 | 4:41 am

This is likely a premultiplied alpha vs non-premultiplied alpha issue. the quicktime importer (ie, using jit.qt.movie) vs just loading the png via a jit.matrix operation is likely decoding the png differently (does jit.qt.movie behave differently ?). Try doing a jit.op pass and multiply (or divide) the rgb planes with the alpha plane, and see if you see a difference.


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