GeorgeF73

I notice in the tutorials that when starting out the author will ask you to create a new file and then have you size it by pixel, i.e. 300 px by 300 px. Is there a difference in sizing it by inches instead of pixels? Just curious. Does it effect the final out come of your project?

Welles

George,

Most of us use and think in terms of pixels rather than inches because it seems to help eliminate any confusion about resolution. As we will have different resolutions on different size screens, 'inches' lack definite meaning. Even when I create for print, typically 15" X 20" @ 300dpi, I think in terms of 4500 X 6000 pixels. When an author of a tute suggests a given size, it generally doesn't matter what size you use. Most often it is just a suggested guideline but occasionally the effect being taught (and suggested settings) will be for a specific size so it is a good idea to follow tutorial guidelines.

GeorgeF73

Now I am curious. Is there any particular reason that you work with your images in 4500 x 6000 pixel resolution?
George

Welles

George,

Most of my print work is sized for USC size archival paper. The paper size is 17" X 22" and I leave a 1" border all around which gives me 15" X 20" printed area X 300dpi = 4500 X 6000 px.

GeorgeF73

Iam not sure I still understand why you work in such a high resolution.
Are you saying that if I want my finished printed photographs to be
20 x 30 that I should work in that size in Photoshop? Would it make any difference if I worked on one that is say, 8 x 10 with the finished print to be 20 x 30?
My reason for asking is that I will be taking some photographs next year where we want the finished prints to be 20 x 30.
I will be using a 5 megapix digital camera shooting in RAW format.

So I guess I asking why it would be better to work on them in Photoshop in the high pixel size.
Thanks for your input.
George

Welles

George,

I'm only vaguely aware of Digital Cameras and RAW formats but I print all my images at 300dpi. Higher resolutions don't seem to yield any gain and 300 is rather a high end standard for the inkjet printers which I use. If you intend to print at 20 X 30 I'd suggest capturing absolutely the most pixel data possible and then checking with the person doing the printing to find out what resolution is needed for the best quality prints. I'd then increase the resolution (pixel size) as needed in Photoshop prior to manipulating the print (sharpening, color correcting etc). If you want the finished print to be 20 X 30, that should be your working size in Photoshop, in my opinion.

The theory is simple. When you increase the resolution of an image, pixels are made up based on the pre-existing pixel data. Adding pixels always diminishes the quality of the image somewhat. Honestly, experience is the only real guide toward a satisfactory end as the desired result is very subjective. Things like how far away you expect the image to be viewed are key.

Lets hope someone else who is a photographer chimes in here...I'm an artist who creates images and seldom even uses photographic data.

wbiss

Yes, if you want to print at the highest quality available!

You should be working on your prints at the highest possible resolution that your camera gives you. [saywhat] OMIGOD, even an 8"x10" at 300 ppi is a whopping 20 MB+. Must be some memory card you have! [stuned]

The point is, if I take that resolution and change the print size to 20"x25" (proportionate to 8x10), my ppi drops to 120. You're, in effect, losing quality/clarity, while your file size remains the same. Now, for a lot of home printers, this quality just might be acceptable. I suggest that you test this out. But, if you're going to have your prints professionally printed (and I'd assume that you are, given the dimensions that you've quoted), you'll want all the pixels that your camera and your software can handle.

Tutorials normally quote pixel dimensions as 99% of the time they're written for web viewing (not print) purposes...

Welles

George,

As you are going to be printing at 20 X 30 inches there is a good chance, I'd say, that you will be sending the images to an imagesetter for high quality prints. All of a sudden a new set of terms, LPI will be added into the mix of PPI, DPI etc. About 4 or 5 years ago a real expert in the field of high end printing, who had worked in the field for at least 50 years, wrote a brief but comprehensive article (he didn't believe in paragraphs, I believe) about the history and use of the terms DPI and LPI and how they relate to printing. He posted it as an entry on Adobe's Photoshop forum for Mac. I kept it squirreled away in an old computer and have pulled it out and put it in a PDF format for uploading. This may help you to understand some of the issues you will be dealing with in advance.

Cheers!
Welles

wbiss

Excellent, straight forward info Welles! [righton]

Thanks a heap for taking the time to dust off the cobwebs and share!

Bubble

Great info Welles - this will definately prove of use to even experienced ps'ers [righton]