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Enlarging images without losing quality

Posted on 2006-11-22
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Last Modified: 2013-12-25
I have several jpg images that I need to enlarge (more than twice the original size). Please give me some tips as to how I can enlarge the images without losing clarity and quality. Thanks in advance.
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Question by:isaacr25
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by:irwinpks
ID: 17997988
First, use an image that is at least 300 dpi. The more "dpi" you have to start, the more information you have which will be included when you increase the size.
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by:isaacr25
ID: 17998125
I have no control over the images that I start with.
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by:irwinpks
ID: 17998150
Ok.. then what you, is set the image to 300dpi, BEFORE you do anything else. Then work with it.
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lherrou earned 300 total points
ID: 17998335
Isaacr25

As you might guess, this is a common problem, and a common type of question. Unfortunately, small images, and JPG format images in particular, provide very little to work with when trying to enlarge them. You just  can't display information which isn't there. Essentially, when you try to make them larger, the software tries to guess, based on the information that is there, what the missing information might be.

Here are a couple of options. First of all, if you have Adobe Photoshop, in Photoshop there are some different settings for the software to use when re-sizing the images. What works best in general may not be best for your specific images. If you look at your "Image Resize" box in Photoshop, you should see that there is a checkmark at the bottom of it, marked "Resample Image". Next to that is a pulldown box for the algorithm to be used to resample the image. You might try experimenting with those algorithms, to see what works best for you - bicubic is usually best for photos, but not necessarily for other images.

Another thing you can try is stepped enlargement. Some images seem to benefit from enlarging in steps rather than all at once. Try using about 5 steps of about 20% of the total enlargement you want, and see if that makes a difference. So, rather than going from 120pixels to 500pixels in a single step, you would go from 120 to 200, from 200 to 280, etc.

You can also slightly oversize the image by about 20%, and apply some light blurring, then resize back down to your final size. This usually works best when the size change is not as extreme as yours.

There are other software packages with slightly different approaches to the algorithms for resize, you might try the FREE Irfanview (www.IrfanView.com), and experiment with the "Resample Filters" in the resize methods area of the Resize/Resample dialog box. There's some paid software if you are prepared to spend some $$$, the best known (although not necessary the best software) of these is Genuine Fractals.

Finally, again I have to point out AGAIN that all of these are extremely limited when working with small jpg images, you are NOT likely to get results that are particularly satisfactory, but they may help a little.

Cheers,
LHerrou
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