DSS question - how to reduce file size afterwards.

[AstroFrog]

Sorry if this is a dumb question - I seem to have been asking a few of those recently!    I'm really not all that good with computers and software.  Must try harder, I think...

So anyway, once you've stacked your subs in DSS, tweaked the settings so that your image looks like it was taken at night again, rather than in some awful fog, and then saved your file, you're left with a 70mb file    Is there a way of shrinking this file down a bit, or is the huge size just the price you pay for getting a better image through stacking?

It's making me wonder how big some of the files are from where people have stacked hours of data to make multi-pane mosaics!

Sounds a bit daft I know, but it would be nice to share my image with friends and family, but I think my internet connection would implode if I tried sending it in it's current size!

Very grateful for any suggestions.

Fred

[oldpink]

there is several ways to reduce the file size but most will reduce the quality as well to some extent

the first thing you can do is resize the image down to a more reasonable size say 800 x 600 rather than 5000 odd bt 3000 odd this will cut the size by a good lump
or you can change to a format that uses compression like Jpeg combined with the above would end up at a couple of Mb

[Earl]

You dont want to shrnk the file pre processing as you will be removing data

When presenting the finished work then consider file size and 8 bit display technology.

[AstroFrog]

Sorry for the slow reply folks, (work takes me away for days at a time so my access here is all too intermittent!) but thank you very much for coming back on this.    

I think I need to take the plunge, get hold of and get used to some proper processing software, so that I can make the most of the data I've got before I worry about reducing the size.  Otherwise, as you say, it's going to reduce the quality too much.

I've got a few days off work coming up so I can see myself taking a crash course in image processing!

Thanks again for your help.

[Cornelius Varley]

If you want others to see your photos, without sending a multi megabyte image, save a copy as a jpeg file.

[AstroFrog]

Thanks Peter, I'd looked for that option, but DSS only seemed to give me the option to save as FITS or TIFF files - did I miss a menu option somewhere?

[Cornelius Varley]

You will need to open the TIFF file in a paint program and then resave as a jpeg.

[AstroFrog]

Great, many thanks for your help, and super speedy response! 

[edjrgibbs]

You can post process in GIMP or PS (among others) then save to a JPEG.

[perfrej]

Just use TIFF with the compress option. It is a non-destructive compression.

/per