PixInsight Forum

PixInsight => General => Topic started by: Philip de Louraille on 2010 November 02 17:02:10

Title: JPG or PNG save results in a less "colorful" image than on screen
Post by: Philip de Louraille on 2010 November 02 17:02:10
If this is a repost, apologies. The bulletin board told me my images were too big so I downsized them.)

OK... this has me a bit confused. I am playing with recently acquired data from NGC 7000 and doing very quick & dirty work to see the results (so no noise reduction for example)
Anyways I get a quite pleasing result on the screen within PI but I save it as a JPG or PING and it all looks 'flatter".
I used Preview on the Mac to show the difference. But why?
Title: Re: JPG or PNG save results in a less "colorful" image than on screen
Post by: Carlos Milovic on 2010 November 02 17:18:00
Could it be related to the Color Management properties? Take a look there...
Title: Re: JPG or PNG save results in a less "colorful" image than on screen
Post by: Ioannis Ioannou on 2010 November 02 17:21:22
JPG is using a compression algorithm that is not lossless, meaning that you will never get the exact image that you are getting with fits (see http://en.wikipedia.org/wiki/Lossless_data_compression )
PNG is lossless but I'm not sure how it will be handled both from the forum image handling routine and/or your browser and/or the individual screens.

I hope this helps
Title: Re: JPG or PNG save results in a less "colorful" image than on screen
Post by: Philip de Louraille on 2010 November 02 21:29:45
It can't be a JPG artifact. Yes JPG is lossy but not to that effect (especially when I save at 90%.) I'll look at the Color Management properties.
Title: Re: JPG or PNG save results in a less "colorful" image than on screen
Post by: Juan Conejero on 2010 November 03 07:19:48
Philip,

That has to be a color management problem. Let us know your color management settings and which profiles you are embedding in your images.
Title: Re: JPG or PNG save results in a less "colorful" image than on screen
Post by: Carlos Milovic on 2010 November 03 07:56:33
I was avoiding to be that taxative :D
Title: Re: JPG or PNG save results in a less "colorful" image than on screen
Post by: vicent_peris on 2010 November 04 02:37:25
Hi,

yes, that is a color management problem. I had the same problem with the NGC6914 image because I forgot to not embed any color profile in the image. Firefox does a nasty job, so it is better to not embed any color profile.


Regards,
Vicent.