Help with printing!

kellylindseyphotography · May 14, 2008

I'm really bad with the math part of photography. If anyone can help, greatly appreciated.

OK the largest picture size print I offer is 11x14. So I need to know what specifications are needed for great quality from that size down to wallet size.

If, when uploaded, my image size is only 72 ppi for resolution, and the w X h is 23x34, how does this translate in prints? Of course, best to order the prints and see for myself, but its just not possible right now.

If I change the PPI to say 150.. how will this change my picture? Will PS try to fill in those pixels appropriatly (but badly?) or is it a good thing? I cannot see a difference when I do it. How does that translate to the print?

Also, I don't need a 23x34 size image, so if I change that to 11x14, how much quality am I loosing? Since I am cutting it in half, am I losing that much quality also?

I am so confused about this stuff, any help is really appreciated and sorry for being such a noob.

Big Mike · May 14, 2008

The standard is that you want to have 300 pixels per linear inch of print size.

So if it's an 11x14 print, you will want a file that is 3300x4200.

For other sizes...just do the simple math. Print size X 300 pixels.

You can use Photoshop to increase or decrease the size of your image. When going down in size, you won't have a problem with quality.
When going up in size, the software has to make up the extra pixels...so the image quality will go down...but with a nice sharp image and a good file, you can easily go up to 23x24. (at that size, you may not need 300 PPI...maybe 240 would be OK but you should ask the printer/lab first.)

kellylindseyphotography · May 14, 2008

So if my camera is shooting at 72 ppi (which is what it says when I open it in ps, that it is 72 ppi, and 23x34) I should shoot in a different setting then? I'd like to keep the 23x34 but have the ppi at 300.

BoblyBill · May 14, 2008

Well, it might help by separating the idea that it's an internal setting in the camera that ps reads to get 72 ppi at 23x34... Let's just take my camera for example. The file size is 3888x2592. When the computer opens the file it automatically assigns the file a printing size, if you will. So lets say it arbiterially (cause is basically does (you can modify this in camera raw)) chooses a 24x16in. sized print. However, a printer doesn't "think" in pixels but rather dots per inch. So, computer takes the file length print length (24) and divids it into the file length (3888) to get the dots per inch (162). If you wanted to print a picture at a certain size, I would first determine the dpi (usually 300) then the size in inches. So in your case, you want the picture to be 11x14 and probably want it printed at 300 dpi then as Mike said your file will have to be 3300x4200 (13.86 MP). That means that in order to get 11x14 shots right out of your camera you will have to have a camera that can shoot 13.86 MP; otherwise, you'll have to resize the shot in ps.

Here's another conversation I had with another member on another forum if this still is a little unclear.

http://photography-on-the.net/forum/showthread.php?t=492669

kellylindseyphotography · May 14, 2008

That is exactly what I'm so confused about. Why does PS open my images as only 72 PPI? And obviously if I increase it to 300, it "makes up" those pixels resulting in poor quality.

HOw then do I set PS to register as 300 ppi as default? (thanks for that reading by the way.. very good but I"m sooo not good at mechanically interpreting that in my brain)

Big Mike · May 14, 2008

That is exactly what I'm so confused about. Why does PS open my images as only 72 PPI? And obviously if I increase it to 300, it "makes up" those pixels resulting in poor quality.

HOw then do I set PS to register as 300 ppi as default? (thanks for that reading by the way.. very good but I"m sooo not good at mechanically interpreting that in my brain)

You are getting there...but you are still a bit confused.

Try to forget about the PPI number...it is practically meaningless. Photoshop (or whatever) will default to 72 because that is for monitor viewing.

The numbers that you need to be concerned about are the actual size of the image, in pixels. Take those numbers, divide by 300 and there is your print size.

If you are resizing for a specific print size, those are the numbers that you need to change.

In the photoshop 'Image Size' box, you can also change the PPI number to 300. This will mean that when in Photoshop, the viewing magnification will change.

Remember, the important thing is the size of the image...not the PPI resolution.

BoblyBill · May 14, 2008

Well said.

kellylindseyphotography · May 14, 2008

hmm ok. so why change it to 300 then?? if it it unimportant ? Why is there an emphasis on that number?

ok so if ihave an image that is 1664x2496 in pixel dimention.. I should divide those #'s by 300? Even if ps tells me that my resolution is 72?

By that logic, the print will be 5.5 x 8. Correct? And thats at 300ppi.?

BoblyBill · May 14, 2008

that is correct. If you had an image 1664x2496 and divided those numbers by 300 ppi then you could get a 5.5x8 inch print at 300ppi. 300ppi is considered standard for a high quality print. You could probably get away with 72ppi if you were say 10ft away from it, but if you were arms lenght you would defenaitly see a degrade of quality.

kellylindseyphotography · May 14, 2008

OK so that would be set by ME correct?

I could leave the pixel dimensions, set the "document size" as 5.5 x 8 and the res (ppi) at 300 and that would be considered "Very high" quality image at print stage?

BoblyBill · May 14, 2008

for that 5.5x8 yes that is correct

Big Mike · May 14, 2008

One thing that we are missing here...is the 're-sample' check box, in the 'Image size' dialog box.

When you open the image size box...you should see the 'Pixel Dimensions' then the 'Document Size' (with the resolution). Below that, you should see the 're-sample' check box.

If you uncheck that box...you can change the resolution to anything you want...and it won't affect the pixel dimensions. It's just changing how the image will be displayed on your monitor.

So...to make things easier and more clear for you. Open the image size dialog, uncheck the re-sample check box, then change the resolution to 300. Then recheck the re-sample box and click OK.
You won't have added or subtracted anything from your image...but then the number might make more sense to you.

Now if you do want to change the size of an image. Open the image size dialog and first go though those steps to change the resolution to 300 (without changing the pixel dimensions). Then recheck the re-sample button and change the pixel dimensions to what they need to be for the print size. This time, when you click OK, the image will be re-sampled to the size that you have chosen.

BoblyBill · May 14, 2008

Again... well said.

kellylindseyphotography · May 14, 2008

Big Mike said:
One thing that we are missing here...is the 're-sample' check box, in the 'Image size' dialog box.

When you open the image size box...you should see the 'Pixel Dimensions' then the 'Document Size' (with the resolution). Below that, you should see the 're-sample' check box.

If you uncheck that box...you can change the resolution to anything you want...and it won't affect the pixel dimensions. It's just changing how the image will be displayed on your monitor.

So...to make things easier and more clear for you. Open the image size dialog, uncheck the re-sample check box, then change the resolution to 300. Then recheck the re-sample box and click OK.
You won't have added or subtracted anything from your image...but then the number might make more sense to you.

Now if you do want to change the size of an image. Open the image size dialog and first go though those steps to change the resolution to 300 (without changing the pixel dimensions). Then recheck the re-sample button and change the pixel dimensions to what they need to be for the print size. This time, when you click OK, the image will be re-sampled to the size that you have chosen.

That was extremely helpful. Thank you.

Big Mike · May 14, 2008

There are also other ways to resize your images for printing...that you might find easier.

One way is to open a new canvas (file/new...) In that dialog box, you can specify the size and resolution of the new canvas or you can choose from a list of presets. They should have most of the common paper/photo sizes and they will be at 300 PPI already. Once you have your new canvas, open your image in a separate window in Photoshop, select all & copy. Then go back to your new canvas and paste the image into it. You can move around the image and use the grips to resize it. This is also handy for when the aspect ratio of the image does not match that of the size you want to print. When you hit enter, the image will be cropped and resized into the new canvas, you can save that as your file for printing.

Another way to do it, is to use the crop tool. When you choose the crop tool, you can enter a size (in pixels or inches) and a resolution. So just enter your print size and 300 PPI and then go ahead and use the crop tool. It will lock to the aspect ratio and when you hit enter, it will resize/re-sample the image to the proper resolution (the proper number of pixels).