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Can I save to jpg format.


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I'm only just getting going with stacking and image processing but have a few teething problems:

1. Why does DSS only save to a TIFF. I struggle to do much with TIFFs and they seem to be huge, like 40+ mb so difficult to upload etc. 

2. I can not justify buying photoshop so am trying to get to grips with Gimp, but again after editing the image seems to be only available in its proprietary format which I can not upload or send to anyon.  

I know there are more issues but any advice on this would  be a great start, thanks  


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The output from DSS is saved as a TIFF because it is uncompressed data, that means all the original pixel values you produced from your stack are preserved in the TIFF. Also the TIFF has a 16 bit per channel depth which means that the faint detail in the image is still there and has not been rounded to a rougher value. Unfortunately this means having a large file size.

Just a word of caution, before you take the tiff file into Gimp you should stretch the intensity of the image in DSS. This is because Gimp only deals with 8 bit image which will destroy detail if you have not stretch the image beforehand.

HTH Dan. :happy8:

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You can convert an image from TIFF into jpeg after you have finished the processing stage or better still use the PNG format. Any editing software that can open the TIFF file should have a save as option.


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Gimp 2.9 can process 32bits per channel which is more than enough for Astro images, older versions of gimp could only process 8bits per channel.

In gimp go to the file menu and select export to have a choice of file format (including jpg).  Gimp makes you do this to prevent you accidentally losing data as when you 'save' it will no longer prompt you to save changes when you close but when you export it will.

You should only convert to jpg once you have completed processing as the jpeg compression loses data.  jpg is also 8bit so you lose colour fidelity. 

As already stated png is a good format for web publishing.

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12 minutes ago, Ouroboros said:

Good. Glad you're sorted. That's an unusual photo, the way US snakes over the aerial and chimneys. Nice one! 

I know, me and some family were camping out, fantastic dark skies over east Yorkshire, but very loud snoring, so I got up at about 3am and took a load of widefield shots and this was just by chance. 

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8 hours ago, spaceman_spiff said:

Nice wide field shot, at that time UM is low so you can shoot it with the horizon for scale. I like the cottage (and the south-facing garden!).


Yeah, very envious of my brothers south facing, very open, very dark garden, at least it's only 25 mins away ? Another shot from the weekend at his house. 


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When you've finished playing in Gimp and are ready to relocate your image do not use the "Save" or Save As" route that would seem the obvious one.

Click on "File" top left on the page and the Menu will appear , halfway down click on "Export As" to reveal another window.

Top of the window type in the name you wish to give the image and then either  .png / .tif / .jpeg  depending on the format you will be using.

Underneath the main box an option reads "All Export Images" , click on the down arrow to the right of it to reveal the formats available , click on the format you require , either PNG image , TIFF image , JPEG image etc ...

I would then use the "Create a Folder" option to export the image into so as to make it easy to find , just name it "Gimp Finished" or similar , the folder will be in the original folder that the image you worked on came from.

Then just click on the "Export" tag at the bottom , various options regarding quality appear then depending on the format you chose , if TIFF then use the "None" option in the "Compression" window that appears , for JPEG use "100%" on the "Quality" slider and for PNG just drop the "Compression" down to "0" using the down-arrow.

Hope this helps ...

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2 hours ago, Steve Ward said:

and for PNG just drop the "Compression" down to "0"

Steve, this isn't necessary from quality standpoint, as PNG is lossless. These compression levels may only reduce file size (but increase saving/opening time).

Though I remember once having a problem with displaying on some forum after uploading a level 9-compressed PNG (level 6 was OK), so perhaps some software might have compatibility issues.

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