Recommended File Preparation for Enlargements

[peterb]

Greetings

I’ve created some interesting panoramas from 4 to 6 2000 x 3000 pixel JPGs via Photoshop Elements. However I’m in need of some sage advice on preparing the files for printing. A nearby vendor offers prints up to 20 x 30 using a nice Epson 7880 Pro inkjet for ridiculously low prices. The operators are somewhat clueless but I’ve seen remarkably high quality enlargements produced, and know local pro photographers use their service. I’ve looked up the printer’s manual and am pretty sure they are using the “normal” setting at 360 DPI. So I’ve basically two questions:

I realize printer DPI and image PPI are fundamentally different, but would it make sense to resample the images to achieve 360 PPI resolution? Or is there some optimal or threshold PPI for the best enlargement quality?

Would better resizing software (e.g. Alien Skin, Genuine Fractals etc.) really produce a visible improvement in quality or is Photoshop’s Bicubic interpolation plenty good enough?

Any insight here highly appreciated!
Thanks <peter>

[revi]

First question: are we talking about 20x30 cm or 20x30 inch?
Second question: what's the size in pixels of the final image?

And is the aspect ratio of your panoramas still 2:3? Panoramas often have aspect ratio's well over 1:2 (height:width),
so you'd end up with white bands above and below your image, or lose the sides of the image (depending on
preference, yours or the printer operators' ...)

For an image of 2000*3000 to be printed at 20*30 cm, I wouldn't do any resizing, just an extra bit of sharpening.

[peterb]

Sorry, it's 20x30 inches. And as to the final pixel count I"ll post details later as I don't have access to the files from here. However it is quite substantial.

The aspect ratio is very short and wide - likely in the neighborhood of 1:6. However In Photoshop I'm able to maintain the correct fixed aspect ratio and then use a canvas sized to match the paper dimensions. This eliminates any problem truncating the left or right ends of the image. And in fact, I can stipulate the color of the bands above and below in case I want it to show through the mat.

Any thoughts on optimizing the PPI for this type of printer, or resizing software?

Thnaks for the reply!

[revi]

So, some quick guesstimates would give an image size around 2500x9000 pixels, where the 9000 have to fit in 30 inch, or 300 pixels/inch.
Sounds like a close to perfect fit, so afaik no need to resize anything (but then, I'm far from the best to ask about printing).

[Manfred M]

Epson native resolution is indeed the 360ppi you list (Canon and HP printers are 300ppi). All that being said is that most people worry far too much about resolution. I print 17" x 22" quite regularly using my Epson Stylus Pro 3880, and have made prints that size from an old 6MP crossover camera. When viewed at normal distances (roughly twice the diagonal of the image) it looks fine and you can't tell the difference of an image sitting right beside it that came from a 36MP camera. If you pixel peep and get your nose right up close, then yes, one can see the difference.

The modern pro printers have some amazing scaling algorithms and I really am impressed on how well they handle just about anything thrown at them.

The only advice I would give you is that if you haven't done so already, convert your image to sRGB. Commercial printers do not seem to have figured out that there are a number of different colour spaces out there and they tend to default to sRGB. If you don't do your own conversion, you might find that your image looks a bit muddy. The other issue that you might run into is that your print will look darker than what you see on screen; I will do a small test print and brighten up my image before I print. This is really the fault of modern screens; they just can't be turned down low enough.

[NorthernFocus]

...The other issue that you might run into is that your print will look darker than what you see on screen; I will do a small test print and brighten up my image before I print. This is really the fault of modern screens; they just can't be turned down low enough.

Yes definately do a test print to check color/brightness. I typically find that I have to kick up both significantly for the print to look reasonably like what I expected. While you're at it you can test the resolution too. What I typically do for testing a large print is to select an area of the image with a good bit of contrast and detail, then crop out a section to print 8x10 at the same resolution as the final image. Then you get a good idea of what you will end up with. But you have to discipline yourself to look at it from the same distance it will be viewed once it's hung, not inches from your nose

[Black Pearl]

If the prices are ridiculously low why not just go and get one printed and see how it looks.

[peterb]

If the prices are ridiculously low why not just go and get one printed and see how it looks.

True indeed - however, one can't really see how good a work could be with a test!

[Black Pearl]

Equally though you have no idea what the image will look like without a test. Their setup could be lighter, darker, more saturated, less saturated, warmer, cooler....etc than your screen so wouldn't a test be the best starting point?

[Manfred M]

Peter - Let me disagree with you. It is the ONLY way you are going to get an indication as to how good the final print will be. The test print has to be a crop of the full size image (not scaled) and should be a representative area of the image. You do have to ensure that it will be done on the printer you are looking at using the same paper.

The test print will let you adjust how light / dark the final product will be, ensure that you are using the right colour space, if the sharpening is okay and if you are not using a colour managed workflow, you can make for colour corrections as well. It may take more than one test print before you are satisfied with it and go on to final.