DPI help - how to increase?

July 22, 2010 7:57 AM

Help! Is it possible to increase the DPI of an image so that it can be printed? Currently, to be "print-acceptable" the image I love would need to be about .5x.75" but I need for it to print about 2x3.

When placed in at current dpi at the current size I need, it looks *fine* if a slight bit grainy, but I really don't think that it is noticeable, and/or adds to the picture's authenticity. But there's a strict rule about DPI that I have to adhere to.

Is there any online software (preferably free or shareware) that can help me to increase the dpi? Is this even possible?

Thanks hive mind!

posted by curiositykilledthelemur to Technology (11 answers total)

Best answer: You'll just have to scale the image to a larger size in whatever image editing program you're using. Computer images don't really have an intrinsic DPI. They have a pixel size, which determines the DPI when the image is printed on whatever size output. So if you jack up the pixel size, the DPI will increase given a constant output size. Of course you're losing clarity, etc, but you've already said that's fine.
posted by kmz at 8:05 AM on July 22, 2010

Yes, this is very easy to do. Gimp is a free, open-source photo editing program that can do this (plus lots more), and there are a variety of simpler programs that can do the same job.

The problem with increasing the resolution of an image is that the program will basically just add extra pixels in between the existing ones. It uses its best algorithms to do this without affecting image quality, but its always going to be noticeable, and the image quality will degrade. View the final at 100%, and if you're fine with the amount of pixelization you see, then you're good to go.
posted by ella wren at 8:09 AM on July 22, 2010

Any photo editing program will let you resize/resample - algorithms for doing it can vary in quality. I've heard that fractal based algorithms will turn up best results, but it depends on what type of image it is - photo, line art, etc.
posted by wongcorgi at 8:18 AM on July 22, 2010

Gimp will work. I think Photoshop has better algorithms if you can access it.

However, it's very likely that your DPI rules were put in place, not so that you'll upscale images, but find higher quality images. If your image is being used with others, it will stand out as being fuzzy and lower quality. You probably think it looks fine, but I'm betting someone somewhere (like your graphic designer/project coordinator/publisher) won't.
posted by fontophilic at 8:18 AM on July 22, 2010

If it's a popular image from the internet, you could use TinEye to find the original source, which is likely to have much better resolution.
posted by MikeWarot at 8:34 AM on July 22, 2010 [1 favorite]

Many image editing programs will have a resize/resample/image size function that will let you increase the size and resolution of the image, however, when enlarging an image for print there is basically nothing you can do to prevent image quality loss.

I would say if you've got access to photoshop use tha. If not use whatever image editor you've already got, chances are it has some tool to do this. If you don't already have a program that can use this I would seek out either GIMP or IrfanView online. Using different resizing methods might let you choose whether you want it to get blurrier or pixelier as it gets bigger, but other than that there isn't much you can do.

Seconding TinEye if you found the image online. TinEye has saved my ass at work in the past, but it will only help if it is an image that has made the rounds on the internet.
posted by cirrostratus at 9:15 AM on July 22, 2010

The rule that you're trying to skirt is meant to prevent exactly what you're trying to do. You can't just magically create information from nothing, unlike what shows like CSI might imply. You can interpolate the missing data, which is what scaling algorithms do, but that doesn't actually create any new detail that wasn't already there before.
posted by Rhomboid at 9:39 AM on July 22, 2010 [2 favorites]

If you have a copy of Photoshop and $160, you can try using a Genuine Fractals, which is designed for exactly what you're trying to do.
posted by Uncle Ira at 9:59 AM on July 22, 2010 [3 favorites]

depending on the type of image you could try converting it to a vector based image ... using something free like the results of:
this google search

Vector images are scalable without limitation or loss of quality
posted by jannw at 7:52 PM on July 22, 2010

The image you have came from somewhere.* That place can also produce the new, larger image that you need. Trying to diddle with the too-small image is tempting, but not as good.

*You haven't told us where you got the too-small image. A computer application? A scanner? A camera?
posted by exphysicist345 at 9:48 PM on July 22, 2010

Response by poster: thanks everyone! my designer allowed me to just 'fake out' as the first poster suggested this one time. :)
posted by curiositykilledthelemur at 11:42 AM on September 21, 2010