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.NET Forum / Windows Forms / WinForm General / October 2007Imaging component for viewing very large JPG's?
I'm searching for a component which is able to show very large JPG images (sometimes more than 30 MB). These are professional scans of large drawings from an archive. I tried DotImage from Atalasoft, but it needs to map a huge block of memory for displaying the image, which often results in memory problems. I am looking for a component that displays the JPG without using so much memory (if that is possible). Any ideas are very welcome Ed I don't know if you are going to be able to get away without using large amounts of memory. I believe to display the image the JPG needs to get decompressed and basically becomes like a plain BMP in memory. You might check in to Paint.Net. It's a very nice open source graphics application built in .Net. You could dig in to the code and see what it's doing and (license permitting) utilize some of it's code.  SignatureAndrew Faust andrew[at]andrewfaust.com http://www.andrewfaust.com > I'm searching for a component which is able to show very large JPG images > (sometimes more than 30 MB). These are professional scans of large [quoted text clipped - 8 lines] > > Ed Hi Andrew, Good idea, but paint.NET has memory problems as well with these images. Ed >I don't know if you are going to be able to get away without using large >amounts of memory. I believe to display the image the JPG needs to get [quoted text clipped - 15 lines] >> >> Ed Hi Ed, There are only a few possible ways to display an image, regardless of the technology. In most, all of the image pixels must be loaded into memory, regardless of whether you display the entire image or not. The other possible way is to approach the problem from one of 2 possible avenues. If you don't have to display the entire image, you read only the pixels you will be displaying. The other way is to keep the file open, and read the pixels each time you paint the image, one set of bytes at a time. This second method is definitely a performance killer, but it does cut down on memory usage. SignatureHTH, Kevin Spencer Chicken Salad Surgeon Microsoft MVP > I'm searching for a component which is able to show very large JPG images > (sometimes more than 30 MB). These are professional scans of large [quoted text clipped - 8 lines] > > Ed Hi Kevin, Thanks for the info. The images must be displayed entirely. Coding this stuff myself goes way beyond my knowledge, I'm mainly a winforms database programmer. Therefore I hoped that some components would work like irfanview or the Windows XP 'picture and fax viewer', for example. These do not seem to have memory problems. Too bad they cannot be used as components AFAIK. - Ed > Hi Ed, > [quoted text clipped - 20 lines] >> >> Ed Does it have to be displayed full size all the time? You could use a graphics library (ImageMagick is nice) to create a scaled down version to show by default. Then simply load the entire image if the user requests it. SignatureAndrew Faust andrew[at]andrewfaust.com http://www.andrewfaust.com > Hi Kevin, > [quoted text clipped - 32 lines] >>> >>> Ed The image must always first be shown as 'fit to screen', and then, if the user wants, be zoomed in. I guess making a 'on the fly' scaled down version with such a library may take a while, or can that be done fast? - Ed > Does it have to be displayed full size all the time? You could use a > graphics library (ImageMagick is nice) to create a scaled down version to [quoted text clipped - 37 lines] >>>> >>>> Ed Honestly, I don't know how fast it will be to resize an image that large. I do know, though, that ImageMagick should be able to do it pretty well as fast as any other image library out there. It's a very mature open source library. If it's possible you may want to do the resize only once and save both the full and smaller sized images for faster display later on. SignatureAndrew Faust andrew[at]andrewfaust.com http://www.andrewfaust.com > The image must always first be shown as 'fit to screen', and then, if the > user wants, be zoomed in. [quoted text clipped - 44 lines] >>>>> >>>>> Ed > Honestly, I don't know how fast it will be to resize an image that large. > I do know, though, that ImageMagick should be able to do it pretty well as > fast as any other image library out there. It's a very mature open source > library. If it's possible you may want to do the resize only once and save > both the full and smaller sized images for faster display later on. It's worth noting that most good bitmap packages do this in some form. Michael > Hi Kevin, > [quoted text clipped - 5 lines] > Windows XP 'picture and fax viewer', for example. These do not seem to > have memory problems. Too bad they cannot be used as components AFAIK. This seems to be a very common question here, everyone is trying to load 100+MB images these days. A lot of programming models cater for this sort of thing by streaming, right back to the early days (eg FTP). But for some reason image compression general doesn't. Michael Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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