How to increase dpi and retain image quality in Photoshop?

This is a question for my sister who is a graphic artist.

Her client has taken a picture with a digital camera and saved it to a disk (it’s a jpg). The image resolution is 72 dpi.

She needs to both enlarge it, and increase the dpi to somewhere around 300 (so that the image can be printed).

When she tries to do it, the image quality declines dramatically. I asked her if it was increasing the dpi that’s causing the poor quality or if it’s the enlarging that’s doing it, and she wasn’t sure. She’s running Photoshop 5.0 or 5.5.

Does anyone have any ideas? Any help is much appreciated

Well I would say that there is not really anything significant her client can do, apart from retaking the picture at a higher resolution.

One method that sometimes works but is dependant on detail, is by resizing little by little, but given that she wants to enlarge AND increase the DPI I think the easiest method is to reshoot the picture. The sharpen tools work but cannot unfortunately perform significant improvements.

Saying that, it can be dependant on how the image is to printed, and how far away the viewer’s eyes will be from the subject.

Itll be enlarging thats casuing the detail loss to answer your other question. Increasing the DPI appears to do so more dramatically than it does, but only because the size of the image on ‘screen’ is being increased so the monitor can accurately show that resolution.

Dan

i’d suggest she get her client to retake the photo at the highest res possible.

Theres nothing much you can do to improve image quality to be honest, you could try some sharpen filters or something but i think it’d be a lost cause.

depending on the image itself, and by how much she actually needs to increase the size, it can sometimes help (weirdly enough) to increase the size step by step (as suggested above) and adding a bit of noise to the image to fake detail (as the noise will be at the final dpi/resolution ). either adding the noise straight to the image, or on a new layer which is then blended in somehow. your mileage may vary, but yes…reshooting with a proper camera at higher res is your best solution really.

As other responsees have sugested, reshooting the picture at a higher resolution is the only way you will be able to both increase the resolution and dimensions.

Perhaps what you don’t understand is why. Although I am surprised your graphic artist sister doesn’t understand this - perhaps she hasn’t had much experience with print work? However, if she is going to have more clients who want work printed, she really needs to understand why you cannot upsample AND upsize a digital pic. You can do one or the other but not both.

Open any image in Photoshop. Go to Image>>Image Size. Click the checkmarks OFF in the two boxes marked ‘Constrain Proportions’ and ‘Resample Image’. Let’s say you’ve got an image 5" x 3" at 72dpi. Halve the width from 5" to 2.5" - what else happens? The height also halves (to 1.5") and the resolution doubles (to 144dpi). Why? Because you have a finite number of pixels that have been captured by the camera (or scanner). By decreasing the size of the image, the existing pixels have been squashed closer together, hence increasing the resolution. The reverse also applies. If you double the image size, the resolution halves because the pixels are spread further apart.

Of course, you can try and ‘cheat’ by telling Photoshop to do both. That is, when you increase the dimensions, tell PS to also increase the resolution - i.e. add more pixels. But what PS is forced to do is ‘guess’ the colours of the pixels it must add between the existing ones (called interpolation). Sometimes it can do this quite well - particularly if there are large expanses of the same colour. But this rarely occurs in photos, and so the interpolated pixels are an estimate based on the colours of the surrounding pixels. And often it doesn’t do a very good job, and the end result when printed looks awful.

There is no way round this that is entirely satisfactory. The best results will only be obtained by capturing the required number of pixels in the first place. That is, take the photo at a much higher reolution and/or a much larger size than the intended output.

The easist way to do it is to convert a JPG into the PSD then higher resolution to 300 in Image Size

sorry forlon, but i thought that it’s irrelevant what format the file is in once it’s opened in photoshop (provided it’s not something with an indexed palette), as “internally” photoshop will just work with any graphic the same way once it’s in memory (i.e. expanding it and work on the uncompressed - or losslessly compressed, whatever it is - data) ?
or am i missing something ? do i get different results if i open a jpg and resize it, rather than open a jpg, save as psd, reopen it, and resize ?

Redux…you’re not missing anything…it’s Forlorn that doing the “missing”.

You cannot take a 72dpi image and scalle it up to 300dpi and have it print at good quality.

This is of course unless the original image had a high pixel dimension. Remember that you can’t simply look at the resolution. There’s nothing wrong with 72dpi images as long as there’s plenty of pixels to work with. For example, a 72dpi image at 2000x2000 pixels is roughly equal to a 300dpi image at 500x500. Four times the dpi at one QUARTER the resolution. It’s a give and take battle.

Forlorn - I obviously wasted my breath…

:lol:

just wanted to make sure that i understood forlon’s claim correctly, before ripping his claim apart…
Eggles…truer words hath never been spoken :wink:

on a related note, does anybody remember all the craze about “fractal compressors” about 2-3 years ago ? how they claimed you could resize/upsample without loss of quality ?
is anybody actually using these, or did they - as i suspect - turn out to work only in very specialised conditions ?
i remember reading a quote somewhere, along the lines of (and i’m paraphrasing) “you can get the best compressor in the world specialised for a single, particular image…all you need is a CS student and lock him up in a basement for long enough”. :smiley:

Well I have ran into this problem aswell, mainly because of clients that doesn’t know what they really want and how to do it but no slaughterfest/trollfest on them you have to work with what you got sometimes.

Well how did I solve this, well I resize the image/picture to 10 times the final size take this case for example.

We have an 5"x5"@72pdi image that needs to become 10"x10"@300dpi, this can look like a horrible thing to do (and usually is) and sometimes there isn’t time or anything you can do to get the pic reshooted.

What I do then is resize the image to 100"x100"@300dpi, add some noise (also some sharpening sometimes depending on the image) then I resize it to its final size of 10"x10"@300dpi.

This is no solution that creates brilliant results and not is it easy on the computer (I run a dual 2200 Mhz @ 2048Mb RAM and it chokes on this sometimes) but it can create something if you need to put it out fast.

Try not to use Digis that only take pics at 72 DPI. The project is going to look like crap if she tries to print it with increased dimensions and increased DPI. Tell her to get a new digi prob made by Nikon or Cannon. Its really the only way.

Originally posted by Sadie Frost
[B]This is a question for my sister who is a graphic artist.

Her client has taken a picture with a digital camera and saved it to a disk (it’s a jpg). The image resolution is 72 dpi.

She needs to both enlarge it, and increase the dpi to somewhere around 300 (so that the image can be printed).

When she tries to do it, the image quality declines dramatically. I asked her if it was increasing the dpi that’s causing the poor quality or if it’s the enlarging that’s doing it, and she wasn’t sure. She’s running Photoshop 5.0 or 5.5.

Does anyone have any ideas? Any help is much appreciated [/B]

use photoshop to make it 300 dpi and the right size, and then “smart blur” it to hell, until it looks like a piece of candy.

lol…just kidding.

(but I have done this before for certain pics that were “once in a life time” and taken on web cam at 72 dpi.)

A reshoot is the only solution to this problem. No one will be pleased with an upsampled image.

I am co-owner of a Print shop in Canada and this is the biggest problem. We have so many people that bring work through the door with 72dpi photos. It drives us crazy. People think if it looks good on the screen, why won’t it look good printed out.

We have quite a few samples printed out to show clients the difference.

Rich

Yeah Rich, I know what you mean. I wish people would learn a lot more about pixel information and how it relates to output on screen and print.

Sometimes “Genuine Fractals PrintPro” works for these kind of problems. It’s a Photoshop plugin. You could give this a try…

][ Med

It can be done, but keep in mind that with photoshop resampling you are adding pixels, therefore photoshop simply does its best to guess the pixel values. E.g. two pixels next to each other will have the approxiamate inbetween value created when the image is enlarged. What you need to do then is to manually retouch the image using, as suggested, sharpen and noise filters, and also the clone tool, blur tool, paint brush etc.

As suggested, when you increase the image size, make it double the intended size, when you reduce to your final size (resample down) some smoothing will occur. Especially if you use a heavy unsharp mask. Using photshop to resample is generally recommeded over any ripping software (production stage).

It depends how many days you want to spend on it :slight_smile: