[fitsbits] Image Extension Question

[Christopher Lawton]

Hello,

I am in the process of writing a utility to read data from FITS files.  The
FITS standard is very clear but I have one question about the Image
Extension.  The standard doesn't define mandatory keywords to scale the
image data, like the BZERO and BSCALE keywords for the primary data.  Is the
convention to use BZERO and BSCALE to scale image data if needed?  Should I
expect the BLANK  keyword to be used for undefined values or is there no
convention for representing undefined values in Image Extension data?

Thanks,
Chris Lawton
clawton at mathworks.com