Custom printing used to be very time consuming and therefore expensive. With digital imaging the results can be both stunning and relatively inexpensive at the same time. The quality of the image is in the hands of the photographer as the file is determining factor. There are more good labs out there than ever before, and unlike the past, they are willing to work with both pros and non-pros alike. Printing your own files can be rewarding, but it is another skill that requires a substantial investment in time and technical know-how that many people find a bit overwhelming.
Printing photos at home is a more complex endeavor than most people realize at first. You have to move into wide format professional and fine art printers to get the best of the options and produce truly fine prints that cannot be distinguished from color prints from a darkroom or commercial printer. High quality images require an understanding of file formats, color spaces, and resolution before you even think about how to run the hardware. Top quality images can be printed on top quality printers, but printing can be an exercise in frustration unless you are willing to invest in a learning curve that is arguably more complex than basic photography. It shouldn't be, but it is. Unfortunately, desktop printers that are less than professional quality printers can be very high in the cost of consumables and are not a viable alternative for high quality photographic printing. Printers also function best when used regularly, so occasionally printing introduces the possibility of clogged heads and other aggravations.
While printing from Photoshop is possible, Lightroom affords the photographer a much greater level of control. Lightroom is designed for management and control of the printing process and adds simplicity in the creation of custom templates. Whatever you use, do not expect click and print solutions. Printing is an art in itself and requires a fair amount of understanding of both the software and the printer to get the best results.
I am now offering Fine Art Printing Services to photographers as well as copying services for artists. Output is with an Epson 24 inch wide format printer and a variety of paper offerings. Archival prints from this printer are estimated to provide a minimum of 100 years stability with the materials I offer.
Printing an image on a desktop printer, sending it to a kiosk or service bureau for printing or providing an image for professional offset printing requires looking at files in a different way. Now we may need to attach the output resolution numbers to the image. The more you know about the device that will used to make the print, the better you will be able to provide an image of the appropriate size in pixels. However, in most cases you do not need to resize the image to match the desired output. The printer driver and software will resize your image for you with better results.
The key is to always think in terms of the size of the image in pixels. If we need to provide someone with a 300 ppi image, we need to divide the number of pixels by 300 to get the numbers of inches the file will provide, or multiply the inches by the desired resolution to determine the needed pixels. A ten inch image at 300 ppi needs to be 3000 pixels in that dimension. Epson printer resolution is 360 ppi, so a ten inch image needs 3600 pixels. The image shown in the Image Size dialog to the right has been changed to 360 ppi in order to determine its native size at that resolution. Changing the Resolution should be done with Resample unchecked to be sure that the image dimensions are not changed. What you are doing is simply seeing what the native image size will be at the resolution you set. This understandably confuses most people as your instinct is that you should provide the printer with the size image you want printed. This is not the case.
If you are printing yourself I suggest using the Lightroom Print module. In the Lightroom print module you simply choose the size you want the image to be and the resolution you want the printer to use and the software handles the rest. You leave the file alone except to crop for content. If you send images out to be printed the same applies. You may be tempted to size the file based on your desired output size, but you should only crop off unwanted pixels or crop to the aspect ratio you desire and leave the file resolution blank. This guarantees that you will not accidentally resample the resolution. The file will retain its original pixel resolution and the print supplier will handle changing the dimensions for you.
As an exercise to help put this into perspective, open an image and open the Image Size dialog in Photoshop. Note the pixel dimensions of the file. Now, with Resample unchecked change the Resolution setting to something else - anything else. Notice that the Width, Height, and Resolution numbers have a lock to their left indicated that they are locked together. This means that changing one will change the others. Changing the Resolution will change the Width and Height numbers in inches, but notice that the Dimensions do not change. The file is intact. The pixels are intact. Nothing has changed except how you are viewing the file relative to a proposed output. You can change these numbers all you like and the file will remain as is.
Let me emphasize (again) that resizing images is only necessary if you need to supply an output file for a specific purpose. Making larger or smaller images from your file should normally be left to whoever is making the print. Most fine art photographers currently print using Lightroom, which has very sophisticated printing capabilities. One of its primary design intents was to be used for printing. Outside printing services may use Lightroom or RIP software to size the images, but will provide the best print if you follow the same basic concepts in cropping your images.
In most cases you should crop to the aspect ratio you want without specifying a resolution in the crop dialog. The other option is to choose the W x H x Resolution option and click the Clear button to remove all specifications. Now you can crop as you wish with no restrictions. Either will retain the most pixels, only removing those pixels outside of your crop. For example, you may wish the image to fit 8x10 dimensions, so you would set the crop tool to match that aspect ratio (4x5) but not enter a resolution into the crop tool.
This will avoid resampling of the file to a larger or smaller size. Rather, it will only remove pixels that will not conform to the desired print ratio. If you choose an "aspect ratio" in the crop tool drop down you will not get a resolution box by default for this reason. If you do a free form crop simply clear the boxes and do not enter a resolution.
Resizing images for specific purposes, such as inclusion in a website, is a similar but slightly different story. There you need to work with pixel dimensions, but again, the resolution is not important. While 72 ppi is assumed by most designers for the web, the only dimensions specified in the code are the width and height in pixels. A web designer may be looking for a 72 ppi image resolution even if the pixel dimensions are accurate. Not everybody gets it.