JPEG Header Information

[Boyd Waters]

Wil:

Although this is certainly the sort of thing that the JPEG-header 
feature was intended for, it is unfortunately a bad idea to rely upon.

Many computer systems think that they know what a "JPEG" file is, but do 
not completly follow the specification, and will blow away your header.

(A friend of mine worked on an image archive for the Fine Arts 
department at the Univ. of Georgia, and discovered this problem the hard 
way...)

-- boyd
National Radio Astronomy Observatory
Socorro NM USA


Wil O'Mullane wrote:
> We have a lot of JPEG images about which lack anykind of infomration in them.
> For the SDSS images we are thinking of adding infomration to a comment block.
> Perhaps this would be good in other instances also.
> 
> Currently we are thinking of adding something like 
> Author="SDSS Collaboration "
> Info="http://skyservice.jhu.edu/develop/jpeghead/index.html"
> TITLE="SDSS Image "
> CRPIX1=744.5
> CRPIX2=1024.5
> CRTYPE1=RA--TAN
> CRTYPE2=DEC--TAN
> CRVAL1=179.948240689264
> CRVAL2=0.101381194295879
> CDVAL1=-3.8008997158114E-08
> CDVAL2=0.000109924630958157
> CDVAL3=0.000110062460780114
> CDVAL4=-4.78845056498477E-08
> NAXES=2
> NAXES1=2048
> NAXES2=1489
> EPOCH=J2000
> 
> or basically the fits keywords. 
> 
> Slightly more info at http://skyservice/develop/jpeghead/index.html
> 
> wil
>