Milky way 108199*81503 gigaphoto or 65500*65500 should be enough for anybody

Few days ago there was a piece of news, that ESO’s Paranal Observatory released most detailed photo of the core of our galaxy made by VISTA telescope in infrared spectrum with resolution 108199x81503.

Unfortunately, they only released it as online zoomable image and 24Gb .psb-file, which you can only open with Photoshop. Photoshop itself can only export it into psb, tiff (unsucesfully, due to 2/4Gb file limit) or RAW formats. And I wanted something which would allow me to cut few pieces for wallpaper...

First of all, here are the results:

1920x1200 2560x1600 2880x1800




1920x1200 2560x1600 2880x1800

Few things about JPEG and ImageMagick

I wasn't able to find UI-based program which can handle such files, so had to switch to console tool ImageMagick (x64). It's better to process large images with Q8 binary version, as it only consumes 45Gb of ram during processing, compared to 72Gb with Q16 (it's using 48-bit internal color presentation, which is an overkill for this task).

Historically JPEG cannot be larger than 65535x65535, but many libraries support only 65500x65500 (and I imagine back then it sounded like unachievable size...).

In order to avoid ImageMagick errors during JPEG saving, one need to disable Huffman-table optimization(apparently symbol frequency counters overflowed) : -define jpeg:optimize-coding=false

I was also able to save whole image into PNG, but no software was able to open it. Also it's size was 22Gb, so I had to stick to JPEG.

Final commands looked like this:

convert -size 108199x81503 -depth 8 RGB:eso1242a.data -scale 50% -quality 95 -define jpeg:optimize-coding=false eso1242a.jpg

convert -size 108199x81503 -depth 8 RGB:eso1242a.data -crop "65500x65500+22500-0!" -gravity North  -quality 95 -define jpeg:optimize-coding=false eso1242a_sq.jpg

Processing time about 30 minutes per operation.

This is where I realized that 32Gb of ram is not enough for anybody :-)

Links & credits

Credit:ESO/VVV Consortium
Released under the Creative Commons Attribution 3.0 Unported license
Acknowledgement: Ignacio Toledo, Martin Kornmesser

http://www.vista.ac.uk/
http://www.stfc.ac.uk/News%20and%20Events/42932.aspx
http://www.eso.org/public/images/eso1242a/zoomable/