working with FITS images
Posted: 2010-06-17T05:28:38-07:00
I'm new to the forum.... I've been using ImageMagick-6.5.7-Q16 for some months. I get error messages when trying to break a 3000 x 1600 pixel 16 bit tif file into a series of twenty 600x400 pixel image blocks. The summarized error is: unknown field with tag 50838 (0xc696) TIFF Read Directory. Tiff warnings 703. This error occurs after:
> convert 750.tif -depth 16 -type Grayscale -crop 600x400@ 750a.tif
So, I converted my image, 750.tif, which is a 16 bit tiff image into a FITS image using ImageJ. I then use the following code in ImageMagick:
I've tried:
> convert 750.fits -depth 16 -type Grayscale-type Grayscale -crop 600x400@ 750a.fits
and also:
> convert 750.fits -crop 600x400@ 750a.fits
Both work, producing twenty image blocks in fits format. However, the resulting image blocks show a reduced greyscale spread. Instead of running from 0 to 32768 as the original tiff and my fits converted images created using ImageJ are, I find the greyscale restricted to 23802 to 32120.
This greyscale restriction appears to occur automatically. I want to eliminate it and get block images with the full grayscale spread from 0 to 32768 or the equivalent.
Is there a way to do this? Could someone explain what is happening with this restricted grayscale I am seeing.... is it a sort of auto-stretch or something?
Rick
> convert 750.tif -depth 16 -type Grayscale -crop 600x400@ 750a.tif
So, I converted my image, 750.tif, which is a 16 bit tiff image into a FITS image using ImageJ. I then use the following code in ImageMagick:
I've tried:
> convert 750.fits -depth 16 -type Grayscale-type Grayscale -crop 600x400@ 750a.fits
and also:
> convert 750.fits -crop 600x400@ 750a.fits
Both work, producing twenty image blocks in fits format. However, the resulting image blocks show a reduced greyscale spread. Instead of running from 0 to 32768 as the original tiff and my fits converted images created using ImageJ are, I find the greyscale restricted to 23802 to 32120.
This greyscale restriction appears to occur automatically. I want to eliminate it and get block images with the full grayscale spread from 0 to 32768 or the equivalent.
Is there a way to do this? Could someone explain what is happening with this restricted grayscale I am seeing.... is it a sort of auto-stretch or something?
Rick