AuthorQuestion
HELP! Detect if a JPG is progressive! REWARD!
Posted on: 16 Oct 2003
ALL I NEED TO DO IS determine if a JPG file is PROGRESSIVE or BASELINE. I have Scoured the web, read half the MSDN library, posted on numerous .net forums, read every GDI+ article in C# Corner and VB.net heaven... and NOWHERE can I find the answer to this question! I have ASP.NET applications that allow users to upload image files, and I need to reject or re-save PROGRESSIVE (multi-pass) jpegs because they can't be loaded or displayed in Flash Player if the are Progressive. AFAIK there is no built-in property in the system.drawing or system.io namespaces to determine this, (although that would be awesome if there were)... so you would possibly have to open the file as a binary stream or something and find the progressive "marker" in the file. I have seen PHP scripts that can do this, so I am fairly sure that a .NET script should be able to as well. PLEASE HELP! I will gladly compensate you with some graphic design, flash development or .net programming if you can provide me with working code to perform this task. I will worship you as a .NET guru if you can do this for me!!!!
[ + ]
AuthorReply
andrew
  • 0
  • 0
Re: HELP! Detect if a JPG is progressive! REWARD!
Posted on: 16 Oct 2003  
You have to use Image.GetEncoderParameterList method. Then you can use one of the enumerations from: EncoderValue RenderNonProgressive and RenderProgressive I have used those for saving, but never tried retrieving the values, which I think GetEncoderParameterList might help.
info
  • 0
  • 0
Re: HELP! Detect if a JPG is progressive! REWARD!
Posted on: 17 Oct 2003  
Hi Werdna... Thanks for the tip, it sounds like a good lead! However, I am still not sure how to actually call the GetEncoderParameterList method in an asp.net application... it does not seem to appear as a valid method of the image object in the VisualStudio.net IDE. The closest match I could find to your suggestion is the system.imaging.encodervalue enumeration detailed here: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemdrawingimagingencodervalueclasstopic.asp but still, I don't understand how this could be used to retrieve a value from an encoded image- it appears to be only applicable to retrieving encoder value constants which can then be applied to an existing image for subsequent encoding. If there's any way you could show me a basic usage example in the context of an ASP.NET application, enumerating the GetEncoderParameterList as applicable to an existing image file, that would be very much appreciated. I know your time is valuable and I'll gladly return the favor in any way I can.
Get Career Advice from Experts
SPONSORED BY
  • PDF reports have never been easier to create. With our included WYSIWYG Designer, you can layout your reports, set up your data source and let DynamicPDF ReportWriter do the rest.
Join a Chapter