Hi EssexBoy - if you mean making the image larger you are going to struggle - most methods I've heard of are limited; to enlarge a raster image file you will be adding data (pixels) through the software's interpolation algorithms. So there is going to be a loss of definition.
Photoshop would be the best tool for attempting this. I'd experiment with the bicubic interpolation settings increasing the image at 10% intervals. In CS3 there is a 'bicubic smoother' setting that is designed for increasing an image's size. Then you can tweak areas of the image using sharpening and blur tools to clean up areas of pixelation.
To make an image smaller is child's play - open it in you favourite editor and typically choose edit/image > image size > then select the %/dimensions you wish to resize it too > click go :)
Found the perfect tool with a free trial as well, has a feature to allow auto cleanup of the image.
I was very surprised to find something this good.
You can't enlarge a photographic 'bitmap' file without *any* loss of clarity.
But, as limbo said, there are ways to make the best of it. Also, bear in mind that each time you make *any* adjustment to a jpeg and then save it, you lose image quality. It may be worth saving as another lossless file format, such as tiff or EPS.
I agree with the above posts especially with the one that suggests Photoshop as the best tool for doing that. I have resized and edited loads of pics with its help and I can assure you that it provides the best quality compared to other different software solutions.
[edited by: Grandmas_Cookies at 12:36 pm (utc) on Oct. 8, 2007]
Has anybody tried IrfanView?
I'm use Microsoft Office Picture Manager for this job
Irfan View is excellent for making multiple thumbnails etc. I use it regulary for my resizing needs. Needs a little hit and trial to get it right the first time though..
Do a search for genuine fractals, its a photoshop plug in specifically for scaling images up. Bi-cubic works but it "undefines" the edges. that software searches for edges and preserves them quite nicely.
Another method is to scale them in steps using bi-cubic. Use Neat Image in between steps to clean out the fuzziness.
Irfanview is very small but yet very powerful program. I do lots of image editing in it including cutting a section of an image, resize, batch processing and many more.
Ill take a look at these thanks