What am I doing wrong?

texassand · Feb 25, 2007

The resoltion, pixel, ppi, dpi aspects of a print confuse me. I've tried everything i can think and cannot figure this out. When i take a pic - I have my Rebel XT set to take a Large jpeg image - its the next biggest option after RAW. Sometimes i will do some fancy editing in PS elements or sometimes I'll just leave pics as is. Then, when I go to upload and print them in a photo sharing website (snapfish, flutterbye, efoto, etc.) it always tells me that my images are "not suitable" for print sizes larger than a 16x20. I want to be able to buy a 20x30 if I wanted to. How do I do this? I took a "print screen" of my desktop showing the picture and "image size" dialog box. Is that normal for them only to be 72ppi strait out of my camera? this particular photo was edited and saved as a jpeg, but even the ones strait out of my camera, uploaded and no editing or compression done are still 72ppi. The pixel amount seems plenty large to print a large photo right? I've tried changing the ppi to 200 but still - it keeps telling me that the image is not "suitable" for anything beyond a 16x20.

Here's the screenshot:
http://i57.photobucket.com/albums/g206/texassand/picturehelp.jpg

Can someone please explain to me how to do this?

thank you!!!

Digital Matt · Feb 25, 2007

DPI, or PPI, means nothing until you print. It only tells the printer how densely to print the dots. Your pixel resolution is divided by the number of dots per inch you'll be printing at, to determine the size of the photo in inches.

2304/300=7.68
3456/300=11.52

Without any cropping, and printing at 300 DPI, your photo would be 7.68x11.52 inches.

If you want to print a 20x30", you should resize your photo before sending it. In the dialogue you have showing in your screen shot, change the resolution to 300, and then change the width to 30. The height will snap to 20", (assuming you have constrain proportions selected). This is going to more than double the size of your photo, so some quality loss is expected. Photoshop has to make up the information. It will be helpful to do some kind sharpening. I would try an unsharp mask at 25%, 20 radius, and 0 threshold. This will add some edge contrast to give you some more perceived sharpness.

This should work. If you are still having problems, I would call or email tech support at whatever printing place you are using and ask them what their requirements are. A lot of them will only give you a large print if they feel the quality will be sufficient. The degree of enlargement you do does affect the quality of the final outcome no matter what printer you send it to, but I'm sure a lot of people don't understand that. That might be a reason why they won't print.

Groupcaptainbonzo · Feb 25, 2007

Firstly the 72 dpi is what your computer screen works on. You will need to print at about 300 pdi as your eyes can detect down to about this level and the ink drops are much smaller than the monitor "Dots".
you should at this size (about 8 Megapixles) be allright up to about A3 ( 17" X 12" very roughly). After this the image will start to degrade because there is just not enough detail captured by the camera to spread out over the printed page. Although if it is a little blurry close up you will find that from a foot or two away it is perfectly acceptable. It kind of depends where you intend to display it.

shingfan · Feb 25, 2007

you got nothing to worry......the word "suitable" means that if you print anything larger than 16x20....the quality would decrease....but it is still doable.....i've used a 6MP picture to print a 40x60 canvas and it showed fine......

each printer has a dpi (dot per inch) setting.......for example....if you have a picture with resolution 1000x2000.....at 200 dpi.....the max size you can print without degrading the quality would be 5"x10" (1000/200 x 2000/200).........if you print anything about 5" x 10".....theoretically.....the quality would be lower than 200 dpi.....because you are not providing enough pixels for each dot........so instead of one pixel per dot...now you are printing 1 pixel per 2 dots.....making the pixels more visible........that's all....but you can still print as large as you want....dont worry (but dont expect super high quality when you are printing large prints without enough resolution.......also a note for you as i've done it before....you dont get better resolution by enlarging the photo......resizing the photo doesnt give you extra pixels)

texassand · Feb 25, 2007

but shouldn't a photo taken with an 8megapixel camera on the largest jpeg available be able to print way bigger than a 17 x 12 clearly? That just seems so small. Is it because I am not shooting it on RAW? Or maybe because of the editing I did with this particular photo/ Because the photosharing site I am using says that it has to be 2700 x 1800 in order to print a 20x30 - so this doesn't make any sense to me because I have more than that in this particular photo right?

Digital Matt · Feb 25, 2007

texassand said:
but shouldn't a photo taken with an 8megapixel camera on the largest jpeg available be able to print way bigger than a 17 x 12 clearly? That just seems so small. Is it because I am not shooting it on RAW? Or maybe because of the editing I did with this particular photo/ Because the photosharing site I am using says that it has to be 2700 x 1800 in order to print a 20x30 - so this doesn't make any sense to me because I have more than that in this particular photo right?

Print quality is very subjective. You might like a 20x30 just fine, where as I might think it looks terrible. 12x17 is considered a large print in the world of photography coming from 35mm film which is only 24x36mm. Getting to an 8x10 is already a considerable degree of enlargement. There are lots of varying opinions on this. Many people feel that digital has surpassed 35mm film, and many feel that it's not even close. In the end, it's up to you, because it's your print. It's always going to matter of your personal taste, and the viewing distance.

EOS_JD · Feb 25, 2007

Check the thread on resolution a couple of pages back from this. You do not require to print at a large ppi to get a good print of a 20x30 image. 180ppi is more than enough and in fact 150 should be plenty. You might even be happy with 100ppi!

Let me try and make this as easy to understand as possible.

For a start dpi only relates to the printers output (or scanning resolution) - nothing else. Many people make the mistake of using dpi instead of ppi (see above). ppi relates only to the number of pixels in your image divided by the intended print size. so in your case
3456/30" = 115.2ppi
2304/20 = 115.2ppi

So without altering your image you can print at 115.2ppi. Now this sounds low and it would be if you were printing a small image (like a 6x4 or a 10x8) but the larger the print you have the lower the ppi value can be because a 30x20 will be viewed from a few feet away whereas a 6x4 will be viewed for a few inches away.

I would probably still upsample a bit to about 150ppi at the intended print size.

The only thing that matters is the number of pixels in your image so a 30x20 @ 150ppi = 4500 px x 3000 px so you are making the image 130% of its original size.

The easy formula to work out your print size/resolution or pixel requirement is

Resolution= pixels/print size

Here's a pretty good link

http://www.steves-digicams.com/techc...uary_2005.html