Need Help with Sizing Images for Lab Prints

I feel like I'm missing something obvious. I don't know what size I should be saving my images as for prints. I export my RAWs as JPEGs out of LR to no particular size or aspect ratio. Is there a size that's relatively universal for clients' print ordering?
I uploaded an image to see what it would look like as a gallery wrap in various sizes, but the image didn't fit any of them, even after adding 3' for the sides. Obviously, this is a problem if a client wanted to order one. What am I not getting?

Thanks in advance!

So, you Export at your desired print size (in inches) with a good ppi resolution (from 200 ppi to 300 ppi) and leave other stuff alone, what happens?

It's possible I'm not being clear enough or there is simply no good answer. Here's what I want to do:
I want to be able to sell prints on Zenfolio in a variety of sizes and with options to order more than just prints- but wraps, canvas, etc. My concern is that the images I upload to Zenfolio will not suit specific products. So, 1.) Do I need to upload a JPEG in every possible size of print? 2.) Should I have clients order wall art products from me and I figure out how it would best fit?
(With the gallery wrap, my image was too big, despite sizing according to lab instructions, so I'm concerned I'm doing something wrong.) Is it possible I'm ignoring something really obvious?

There is no universal one size fits all crop. Your images from your camera are in a 3:2 aspect ratio- so if you aren't cropping your images at all, you can create 4x6, 8x12, 10x15, 20x30 etc. prints without any adjustments.

If you are cropping images for prints, you will crop in your desired ratio for the image you are trying to create. If you are having your customers order through you, you can re-crop your image for the desired print size once they place an order. If you are outsourcing your print orders, you probably want to crop the images based on the print sizes you have available prior to showing to your client to order. Using a raw editor (I use lightroom), you can crop your images to any aspect ratio you want.

Edit- you answered while I was typing- you can either upload jpegs to the aspect ratios offered through zenfolio, or set up your zenfolio account so you have to approve all print orders- once the order is placed, you can then crop as needed.

Thank you! This will be the first time using Zenfolio, so I didn't know about the approval option. That's good to know! I use Lightroom, as well.

Printing FAQ. Ask your lab for spec (eg sRgb 300ppi jpeg) and process to those.

Thank you for that. Very helpful. I don't use PS, so some of that is lost on me, unfortunately. It would be great to have that info tailored to Lightroom users.

http://damiensymonds.b​logspot.com …lling-digital-images.html

glasllyn wrote in post #17236074
Thank you for that. Very helpful. I don't use PS, so some of that is lost on me, unfortunately. It would be great to have that info tailored to Lightroom users.

This will depend on how you are exporting the image from LR. If you are simply going to process the image and use the normal export dialogue then it becomes quite simple. First crop the image to match the aspect ratio of the print. If the ratio you need is not in the list of ratios in the crop drop down, then enter it as a custom size. All of the other settings are done in the export dialogue. In the File settings section set the colour space to sRGB (which is the usual LR factory setting), unless the lab has told you to use a different colour space setting. Use JPEG as the file type and set the quality setting to 80.In testing there is no visible difference in the file, that I could measure using Photoshop, between using a Q100 setting and the Q80, although the file is about 40% smaller.

Then you will need to move on to the Image Sizing section. Again this is actually pretty simple. Tick resize to fit, select Width and height, and then select either In or cm instead of pixels. This will ensure that the image is output at the correct size for the resolution of the output device/printer. In the resolution box set the resolution to match whatever the lab has told you it needs for the printer, or just set it to 300. In the sharpen section you have the option to add output sharpening. I usually use it, and would set it for the outptut type that is most suitable, Gloss paper for glossy prints, matte apaer for everything else, unless you are only viewing the file on screen, but here we are talking about files for printing. Personally I set the Amount to high, but that is personal preference. There is no way to preview output sharpening, as to apply it for viewing, the file conversion has to be done anyway.

Once you have set this up of course you can save it as an Export preset to enable you to reproduce the settings instantly when you need them again. If you use the Print module to do your printing from, all of these settings are also there, The only real issues if you are sending out to a print lab, is that you need to set some settings in a print driver, if you do not have a printer, or your printer driver doesn't support certain custom settings, then I suggest using a PDF printer, most simple PDF printer drivers allow you to customise all of the settings that you might need. mostly that is paper size. If you are doing ab prints at sizes that your desktop printer might not support this is the way round it, while using the print module. You will need to set the module to print to file, after which if you have a look at the various settings in the right side tool bar you should be able to find all of the settings that I have mentioned above. The print module will allow you to see a preview of how your print should look, but it is a little harder to use.

Alan

You need to be prepared to adjust each image to suit the latest order, its impossible to second guess what people want!

Just remember the golden rule of 200 to 300 ppi at whatever size print the customer orders. I've also got into the habit of leaving the final sharpening to the very end of the post processing.

Thank you both. Those were both very helpful and concise. I was wondering about both cropping AND resizing in the export process. I've been very wary of the sharpening aspect as I can't see the results and I do not do my own printing. I suppose some test prints are in order.

Thank you for the Golden Rule. I have it set to 300, and I do wonder sometimes about when to reduce that. My lab (Miller's) asks for Q100, so I keep it set there. I would be interested in knowing when it would be appropriate to change that.

Thanks, Damien!

I have done quite a bit of testing, mostly using various layers in PS with each being a copy of the same image at different export settings. Set the blend mode to subtract, and what you are left with is the difference between the layers. I compared a TIFF along with 13 different JPEGs. Between the maximum setting and 80% the biggest variation I could find in any pixel in any channel was 5. Whats more over 99% of pixels had zero difference. When it came to file size the 100% size JPEG was the same size as the TIFF, while the visually indistinguisable 80% was around 40% smaller.

Given this I have absolutly no problem using 80 as my setting when sending files out for printing. My settings are pretty much as above, although I use a colour profile supplied by the lab, at 300ppi, which is the requirement of the lab. I usually print at 16×12 using a service that makes zero changes to the file, so no worries about auto corrections screwing up the image.

Alan