Help with large printing process

[Cozen]

I'm pretty new to printing with the exception of simple 8.5 x 11's on my inkjet printer. I'm looking to print a few pictures in larger formats say 16x20 or a little larger, whatever the next few sizes are.


As for image processing to prep for printing, what needs to be done? What is a good way to check if my image will print well in a large size? What DPI should I aim for etc etc? (i'm really clueless about this stuff)


A few details about how I shoot. I use a Canon 40D and shoot in Raw. When I process the picture and save it on a disk or whatever to send it to, say Kinkos, what is the best file format?





Any help for this noobie s appreciated, thanks.

[Vlad Xp]

Here's my understanding of this process:

A high-quality print process requires your "Document Size" resolution to be 240 pixels per inch (ppi). A 300ppi is even better. You can check the Document Size in Photoshop from "Image -> Resize -> Image Size" menu.

Your 40D makes images with the maximum size of 2592 x 3888 pixels. That means, without resizing the image, straight from the camera, your maximum printed image size can be 10.8" x 16.2"

2592p / 240ppi = 10.8"
3888p / 240ppi = 16.2"

If you want to print it larger, then, obviously, you must resize the image in Photoshop. What's important is that you don't decrease the "Document" resolution below 240ppi.

For example, you'd like to make a 16" x 20" print. Your image resolution must be 3840 x 4800 pixels.

16" * 240ppi = 3840 pixels (height)
20" * 240ppi = 4800 pixels (width)

Here's the resizing procedure in Photoshop (Elements or CS) that you must follow.
In the "Resize Image" window:


*Enable "Constrain Proportions" option
*Enable "Resample Image" option, so that the Document Resolution will remain at 240ppi
*Select "Bicubic Smoother" option
*Specify the "Document Size" height of 16 inches (notice that your width will automatically change to 24 inches.

Since 16" x 20" aspect does not match the original document ratio, you must crop it manually.

As a last step, sharpen your image using your favorite sharpen method.

If your print shop allows "TIF" files, save your file as "tif" with no compression, otherwise, stick with JPG, highest quality.

I hope this wasn't too confusing.

[Cozen]

Thank you so much for taking the time and posting this. This is exactly what I was looking for.





Just a few questions. Does the print size change for 300ppi? Because my native resolution for my images is 2592p x 3888p at 300ppi. So would this be bigger than 10.8x16.2? or the same?


Also is anyone else having opening a RAW image, and saving it as a jpeg? The save as jpeg option doesn't appear until I resize the image to something smaller. Am I missing something here?

[Vlad Xp]

No problem!

Yes, if your document resolution is 300ppi, then you are reducing the maximum print size because you are using more pixels on paper in one inch worth of space. Frankly, I don’t see that much of a difference in print quality if you print at 240ppi, vs 300ppi.

Same rule applies: 2592px / 300ppi = 8.64" instead of 10.8" (document height).

You can even print at 200ppi. You'll get a bigger print size (12.9" height) but your document sharpness will be reduced, and you'll have to view it a bit further away for that to be acceptable. Look at a billboard. Those are typically printed at 10-15ppi. Stand up close to it, and you'll just see a bunch of giant dots, but at a typical viewing distance, they look normal. You can print your 40D image up to 288 inches-wide at 15ppi, but you must stand 200 yards away from it for the image to appear sharp.

I'm not sure about your saving RAW to JPG issue. Which application are you using when you try to save?

[Cozen]

I'm not sure about your saving RAW to JPG issue. Which application are you using when you try to save?

I'm using photomatix to create an HDR file which saves as a tif, then I open it in CS4 to do levels and whatever else I want, but I can't save it as a jpeg unless I shrink the image size.

[Vlad Xp]

Photoshop won't let you save the file as JPG unless you flatten the image first. Do you adjust levels on a separate adjustment layer, or directly on the background? In any case, I'd make sure that the images is flattened first. Other than that, I'm out of ideas. Maybe other Photoshop gurus here could solve this mystery?

[jimr]

As Vlad Xp indicated send in the best format your service can accept.


I usually start a shooting session with a few shots of the a Color Checker Palette (or <span id="rptItems_ctl00_itemList_lblShortCopy" class="r-shortcopy"]Gray Scale Card) and have those printed to double check mine and the color calibration of the printer. Even getting the subject to hold the Color Checker Palette (or <span id="rptItems_ctl00_itemList_lblShortCopy" class="r-shortcopy"]Gray Scale Card) for a few test shots. On difficult lighting shots I have put the color checker palette passport (or <span id="rptItems_ctl00_itemList_lblShortCopy" class="r-shortcopy"]Gray Scale Card) open in a comer that I could use as a reference but crop out of the final print (or place behind a mat).