twb@cbnewsh.att.com (thomas.w.beattie) (09/18/90)
I have some .gif files in GIF89a format. Cshow 8.11b 2/25/90 won't display them. Is there a newer version of Cshow that supports 89a? Would someone please upload it to Simtel or make it available for anonymous FTP. Anyone care to explain what is new and improved about GIF89a? and why it isn't backward compatible? --- TIA, Tom Beattie att!hoqaa!twb t.w.beattie@att.com
twegner@mwunix.mitre.org (Timothy Wegner) (09/21/90)
twb@cbnewsh.att.com (thomas.w.beattie) writes: >I have some .gif files in GIF89a format. >Cshow 8.11b 2/25/90 won't display them. >Is there a newer version of Cshow that supports 89a? >Would someone please upload it to Simtel or make it available for >anonymous FTP. >Anyone care to explain what is new and improved about GIF89a? and why it >isn't backward compatible? >--- The older CSHOW *should* display most GIF89a files. The new spec allows use of extension blocks to store comments and application-specific information. The previous spec (GIF87a) did not allow the use of these extension blocks but *DID* specify how to skip over them - thus any decoder which doesn't choke on the "89a" in the signature (as some do) should skip over the extension blocks and display the image justy fine. Some other enhancements include text display and timing parameters for images. FRACTINT version 14 creates GIF89a files - the older Cshow buzzes angrily and makes the "89a" flash on the screen - but then goes ahead and correctly decodes the image. The new Cshow is the only decoder to my knowledge that fully supports the new spec. Cshow can be downloaded from the Compuserve PICS forum - it is in lib 3. I believe the file is called "CSHOWA.ZIP" - might be "CSHOWA.EXE".
dlawson@grebyn.com (Drew Lawson) (09/24/90)
In article <1990Sep17.200013.10204@cbnewsh.att.com> twb@cbnewsh.att.com (thomas.w.beattie) writes: > >Is there a newer version of Cshow that supports 89a? Yes, Cshow 8.21a is out. I got it off CompuServe. Sorry, I don't have FTP access. >Anyone care to explain what is new and improved about GIF89a? and why it >isn't backward compatible? One factor I know is that 89a allows for 'extension records' which allow a system to store additional information in the GIF file. I got this from the FractInt documentation. They store the fractal computation information in the GIF file so that you can store partially computed fractal images. I assume that the format has other changes, but older viewers wuold not know to ignore these records. -- +--------------------------------------------------------------------+ | Is life an illusion? | Drew Lawson | | Or does it just seem that way? | dlawson@grebyn.com | +--------------------------------------------------------------------+
twegner@mwunix.mitre.org (Timothy Wegner) (09/25/90)
dlawson@grebyn.com (Drew Lawson) writes: >One factor I know is that 89a allows for 'extension records' which allow >a system to store additional information in the GIF file. I got this >from the FractInt documentation. They store the fractal computation >information in the GIF file so that you can store partially computed >fractal images. I assume that the format has other changes, but older >viewers wuold not know to ignore these records. Slight correction on the last part. The GIF87a spec specifies skipping extension blocks, so the new features should not bother older decoders. However, a few decoders (eg VPIC) refuse to decode anything without the GIF87a signature. Cshow (the older ones) beep at you, but still attempt to decode. I do not understand why the originator of this thread was unable to decode GIF89a files with an older Cshow - I have done it many times. >-- >+--------------------------------------------------------------------+ >| Is life an illusion? | Drew Lawson | >| Or does it just seem that way? | dlawson@grebyn.com | >+--------------------------------------------------------------------+
dlawson@grebyn.com (Drew Lawson) (09/27/90)
In article <twegner.654269448@mwunix.mitre.org> twegner@mwunix.mitre.org (Timothy Wegner) writes: >GIF87a signature. Cshow (the older ones) beep at you, but still attempt >to decode. I do not understand why the originator of this thread was >unable to decode GIF89a files with an older Cshow - I have done it many >times. I had an older version of Cshow (from CompuServe within the year, don't know the version) until I started playing around with FractInt. When trying to view the GIF files saved there, it would start out, display part of the screen, beep and quit. The file information screen would come back up flashing the 'GIF89a' version tag. -- +-------------------------------------------------------------------------+ | Is life an illusion? | Drew Lawson | | Or does it just seem that way? | dlawson@grebyn.com | +-------------------------------------------------------------------------+