increase jpg size and keep quality?

I have saw heard of these software programs that claim their software can keep the quality of a pphot as the size increases. Is there any recommended program that can do this? I'm not expecting miracles but would like to increase a photo about 75% in size while keeping most of the original quality as possible.
thanks for any info

 

Image Analyzer (free) has always worked well for me:

http://meesoft.logicnet.dk/Analyzer/

 

thanks, will give it a try

 

http://www.freewaregenius.com/how-t...ization-and-quality-degradation-and-for-free/

 

keep in mind that JPEG is a lossy compression format.
so every time you process a JPEG, then save it as a JPEG, compression artifacts creep in.

if possible, it's always preferable to use a non-compressed format, especially if it's something artistic.

one of the best software to increase image size is PhotoZoom, but it's not cheap.

 

I think it´s not possible to increase the size of an image and keep the quality. To increase the size, it´s necessary to add new pixels, which are calculated (interpolated) from the existing ones. The quality of the result depends on the algorithms used, but it´s always lower that the original. Some programs allow the user to try different algorithms and compare the results.

 

I tried this one and increase the size by 50%. Then I compared what the program made to the original photo enlarged by 50% and you could definitely tell the program helped.

 

Yes, the OP might want to convert to lossless TIFF as a first step (if the image resizer supports it).

Also regarding JPGs some programs have a compression Vs quality slider.

 

SouthPark suggested Image Analyzer (free) did you try this program and if so what did you think of it? Thanks!

John

 

I have not yet tried the one suggested by SouthPark. If I try it I will let you know the results.

 

I find that Image Anlyzer works best using the Wiener filter with m=4 for resizing, up to about 150% if the original was of sufficient quality.

 

I converted to TIFF then used Image Analyzer with the Wiener filter (150%) and it was the best final picture of all I tried. These are all very good freeware programs. Thanks for all the help and suggestions to everyone.