FITS LRGB Stacking In PI Then Opening in PS

[Radar]

Hi,

After I had added my luminance channel to my RGB image in PI (this is a fits file), I end up with an image with four channels (LRGB). Anyone know how to then open this in PS without losing any image quality? PS cannot open an LRGB fits file. I've been advised to make the RGB image one channel first and then add the L channel for a total of 2 channels, but I think this may lose some image quality. Any tips and tricks to this would be very welcome.

Regards

Ray

[Warhen]

Ray, the addition of luminance in PI is done in the CIE Lab space, so that the luminance info inhabits the lightness (L*) channel of the image. Though PI's processes continue to allow access to the L* after LRGBCombination, it's effectively a three channel RGB image. The reason that Photoshop can't open the image, is that neither FITS or XISF are native file formats for it, and all of its features can't really handle a 32-bit file. You can get a FITS reader for PS such as FITSPlug or FITS Liberator, but I'd recommend just saving the final from PI as a 16-bit TIFF. By that point, the header information isn't important, and PS can better handle a 16-bit TIFF, which is virtually lossless for further tweaking. I've found that PixInsight has replaced my reliance on PS.   

[Radar]

Hi Warren,

Thanks for that. I agree, PI is replacing my use for PS. I've been using your manual to learn the PI craft. I just want to be able to use some features in PS for final tweaking. I'll convert to a 16bit tif for any PS stuff.

PI certainly has a learning curve, but certainly has some extremely powerful features to.

Thanks for your help buddy.

Ray