Re: Imaging component for viewing very large JPG's?

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

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.

--
Andrew Faust
andrew[at]andrewfaust.com
http://www.andrewfaust.com


"Ed Sonneveld" <esonneveld@xxxxxxxxxx> wrote in message news:4726e74b$0$237$e4fe514c@xxxxxxxxxxxxxxxxx
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

"Andrew Faust" <andrew@xxxxxxxxxxxxxxx> wrote in message news:3FE77DEE-7D7A-46A7-96FB-120B6724549D@xxxxxxxxxxxxxxxx
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.

--
Andrew Faust
andrew[at]andrewfaust.com
http://www.andrewfaust.com


"Ed Sonneveld" <esonneveld@xxxxxxxxxx> wrote in message news:4725d36b$0$241$e4fe514c@xxxxxxxxxxxxxxxxx
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

"Kevin Spencer" <unclechutney@xxxxxxxxxxxx> wrote in message news:Od29Y4hGIHA.3600@xxxxxxxxxxxxxxxxxxxxxxx
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.

--
HTH,

Kevin Spencer
Chicken Salad Surgeon
Microsoft MVP



"Ed Sonneveld" <esonneveld@xxxxxxxxxx> wrote in message news:4724f63b$0$242$e4fe514c@xxxxxxxxxxxxxxxxx
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











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