PICT2: Resource Fork Versus Data Fork Storage



I need some information on PICT2 data structure. I do digital photo-retouching
frequently creates individual files 20MB to 30MB, or larger, especially when
scanning at 4000 lines per inch.

I use film recorders, most of which are QuickDraw-based and accept PICT2 as
input. I had a problem trying to create a 20MB PICT2 file from my scanning and
retouching software (BarneyScan XP and PhotoShop). Is this a problem with the
image software, or is it a PICT2 limitation?

We examined the PICT2 documentation in "Inside Macintosh, Volume 5." In PICT2,
the picture length in the header is ignored (set to -1). Does this mean that
this is variable data length?

The limitation that you are most likely running into is a resource size
limitation rather than a PICT2 format limitation.  If the application stores
the pictures in the file's resource fork (as a PICT resource), it is
understandable that you can't create a 20MB picture.  The maximum size of a
file's resource fork is 16MB.  This is because a 3-byte number is used by the
Resource Manager to offset into the resource map.

If your application can store the images in a format that uses the file's data
fork, you should be able to create and use images larger than 16MB.


Published Date: Feb 18, 2012