very large images, use in PI

[Marcovanderkooij]

Dear PI, and or anyone who might be able to assist....

First of all thank you for creating this great software package. I am using it mostly for astrophotography.
My question is related to an attempt to use it for a very large RGB image: 28000 x 30000 and about 2.8 Gb. I'd like to use some of the PI (1.08.3.1123) functions.  However when I try to load it into PI this is not successful: It continues for many minutes "reading" the image.  I suspect that some of the settings are not optimized for this file size.
My computer has sufficient RAM and HD (SSD).

Can you please advise?

Thank you,

Marco

[oldwexi]

Hi Marco!
Just created and saved a RGB file 30000x28000 pixels in XISF format. (Using PixelMath)
Final saved file has 4.7GB.
This file loaded within a few seconds into PI. (PC has RAM 16GB, SSD 20GB free, 64-Bit)

With which software did you create this large imagefile and in what format did you save it?
What is sufficient Ram and SSD free space in your terms?
Why do you use an old version of PI.
More info is needed ....

Gerald

[msmythers]

I just want to add a little here to what Gerald was doing. First my computer is running Windows 7, 6 core AMD, 16GB ram and 2 SSD's. The anti-virus was on during these tests but I have PI and all folders associated with PI excluded.

I decided to use a real image. I took an 8-bit image of the Pacman(2560x1688) and changed the size to 30000x28000. I then saved that as a xisf, tiff and jpg just for comparisons. The tiff and xisf files saved as 2.47GB while the jpg compressed the image to 89GB at 100 percent. I had no problem working on these images but it was not instant operations with tools like curves which normally is very responsive. Saving the file takes a little time but not long. Loading also is a little long but under 20 seconds.

Next I decided to try to save the image as 32-bit floating. This is where Windows burped and PI came back with an out of memory error. PI did not crash. Everything was still running. My first thoughts was Windows Page File. That was set for the OS to decide what was best. In this case 16GB with a max of 24GB. I changed the page file to 48GB upper and lower limit. This locks the amount. After restarting the computer and verifying the page file was 48GB I went back to PI to save the file as 32-bit. This time no problem other then it took a long time, 5 minutes+. The saved file was 9.8GB. I then restarted PI and opened the 32-bit image. This took about 45 seconds but it did open. I then tried using Curves and while I could make changes to the image it was painfully slow, over 5 minutes.

Opening an image was not a problem but if I was going to work with images of this size with PI I would want a lot more ram and many more cpu cores. I would probably also want to be using Linux and a ram disk.



Mike