punkerz123 wrote in post #8383673
Does this change have any negative effects?
Yes. You loose quite a bit of data.
Also; if you are working in ProPhotoRGB, you should never use 8bpc IMO.
tonylong wrote in post #8383677
Like he said. Also, if you plan to use the jpeg on the web, make sure your image is in the sRGB color profile. If you go to Edit/Convert to Profile, the dialog will tell you what color space the image is currently in and you can choose the profile to convert to.
It's best to do this before going from 16bpc to 8bpc.
In fact, it's better to not go to 8 bpc, but use "Save for web" instead.
If the file is too big, create a copy, and save that as a (downsized as needed) jpg.
Alternatively (what I would do): Work on the .tif or .psd in Photoshop in 16bpc, then save and close. It will be added to the Raw image in Lightroom. (They will be stacked).
Later it's easy to export the images from Lightroom as a web gallery for instance.
In all cases: If your image is in ProPhotoRGB, converting to sRGB is always done using relative colorimetric rendering: So any colors outside sRGB will be clipped. Watch out for that.
tonylong wrote in post #8383677
Lightroom works in ProphotoRGB, and you can either have Lightroom convert the photo to sRGB as it sends it to Photoshop, or Photshop can convert it to sRGB as it brings it in, or if you are saving for the Web, you want to manually convert it in the way I mentioned above.
Save for web from PSCS3 on has the option to "convert to sRGB" for you (tickbox).
I wrote more in depth about save for web on my blog here
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