JPG's

[Carl]

Just took 47 pics of Lagoon nebula only to realise they are JPG's not RAW settings. Have I waisted a night or are they usable in Deepsky Stacker

carl

[Aster]

How can it be wasted, you have 47 images :)

Convert them to .TIF file format and stack them in DSS.

Then do your usual in Photoshop or whatever

[matt]

But aren't they already compressed during the jpeg conversion process?

What's the point of converting them to TIFFs if you're not getting any true extra information as a result of the jpeg to TIFF conversion? Aren't you just making the files unnecessarily larger without any true gain?

[Hagar]

Carl From memory DSS will stack JPG images without the need to do anything to them. The only problem would be if you are using calibration files in a larger format.

[iceman]

You can still used them, you just won't have the quality or depth of data.
Just use them as is, no need to convert them further.

[Aster]

Every time you play with a JPG file you lose some detail.

TIFF's on the other hand are lossless.

[matt]

Yes, I understand that.

But my point is: why bother converting the jpegs to TIFFs anyway, since you're not gaining any additional information as a result of the conversion. I would have thought all you're doing is making larger files.:shrug:

Or does DSS force you to work with TIFFs?

Wouldn't you be better off capturing in RAW and converting to TIFF...rather than converting them to jpeg (in camera) and then converting to TIFF later?

[deadsimple]

I've never used DSS, but I agree that unless the software requires a TIFF input I don't see why you'd convert all the JPEGs to TIFF. No extra detail produced and if you're not going to be quick-saving over the top of all the original frames, then the source format shouldn't matter. Just choose a lossless file format at the end when you save the processed result, as you're probably going to do - and go for the less lossy format next time you capture.

[MrB]

I think Aster is worried that every time you do something to the image in an image editing program, the program saves the result as a JPG(or whatever format it was opened as), therefore compounding the compression problems each time something is changed.
So I think he's not saying you'll gain any detail, but that you will lose less detail with each edit.

However, to the best of my knowledge, this is not the case.
Programs such as Photoshop have the image stored in a 'scratchpad' as raw data, it's the raw data that is edited, free of compression.
Only when you choose to save the edited file is the compression used.