Category: Digital Photography
51. What are some of the basics of printing digital pictures?
Lets talk first about cameras. When it comes to printing, the biggest contributor to quality is going to be how many pixels (short for picture elements) are used to make up an image. You will typically hear a camera described as a 4 megapixel camera or whatever it is. This means that the camera is capable of being set to take pictures that will shoot an image that will contain 4 million pixels, or close to that. For example, the Canon G2, at its highest setting shoots an image 2272 x 1704 pixels, which is nearly 3.9 million.
This is important because the more pixels that are used, the more detailed the image will be. You are able to make larger prints and do more cropping than a camera with a lower resolution.
If you plan on making prints (as opposed to web use) with your camera's images, you should shoot as the highest resolution setting. Additionally, cameras may offer "quality" settings that are the same resolution but have different compression ratios. The standard format for digital cameras is JPEG and this format allows for various degrees of compression. You can get more images on a film card with a higher compression rate, but the quality may suffer.
Additionally, an image is going to be in RGB mode, that's Red-Green-Blue. You should leave it in this mode and really only need to change to CMYK in your image editor for offset printing purposes.
After the picture is taken, it gets downloaded to the computer. It is then ready to be worked on in a program called an image editor. Adobe's Photoshop™ is the number one commercial grade image editor.
Whatever you use though, you will want to be able to size, crop, and rotate if necessary, if not even do some filtering and other manipulations like special effects or retouching.
Basically though, your main consideration is to get it ready to print to a certain dimension. In Photoshop, you can program the crop tool to not only crop to a certain size, but a certain resolution as well. A common question that comes up is what is a good resolution. You will get a variety of answers to this. Personally, I set my crop tool to a setting of 240 ppi (pixels per inch). Higher than that is not necessary and will result in a larger size file. Some people go for 150 ppi and that may be fine but much lower than that will likely result in a course and lower quality print with a loss of detail.
Now, some people advise to use the Image Size dialogue box in Photoshop. You simply put in one dimension you want and the other dimension is figured according to proportion provided that option is set unless you want to put someone on a diet by making them skinny. The idea here is you turn off "resampling" and your pixels are left alone. These are the purists among us.
With the method I advise, Photoshop is going to need to "make up" some pixels to get the job done. I think it does a darn good job of doing that when set to "bicubic".
Additionally, I want to crop the image to a very specific size for both length and width and that and the resampling is all done in one step. You can even use the crop window to straighten a crooked image.
Once the image is sized, it should be saved as another file so you leave the original alone to be manipulated again another time. Photoshop provides options for a variety of formats to be saved in depending on your need. If there are no layers involved and you know you will not be making any more changes, then JPEG is fine. The JPEG format is what's called "lossy" meaning everytime you save it, it compresses again and loses some information degrading the image. With enough repeated saves, you will notice this loss of quality. If you save it this one time, don't worry about it and you have a smaller file that takes up less hard drive space than if you saved it as a TIFF or a PICT or whatever.
So now the image has been sized and is ready to print. You will now go into the Print Setup dialogue box and select the paper size and the image orientation. Typically a horizontal is called "landscape" and a vertical is called "portait".
Next, go into the Print dialogue. You will select the grade paper and the printing resolution. The type of paper, or media, is extremely important to the final quality of the print. Typically one is better off using the same brand of paper that makes the printer. You will find settings for glossy and matte surfaces and maybe transparencies as well. This determines how much ink is used and the media type should be selected as close as possible to what you are using.
Print resolution on an ink jet printer is measured as dpi, dots per inch, often confused with ppi. This is how many dots of ink are used to make up the image of the print. The higher the number, the higher the resolution. If you have it set too low, you will have a low resolution, course looking print in which you can actually see the dots. You may even be able to set it too high and lay down too much ink that puddles. Epson's 1440 dpi gives a very nice and smooth gradation of tones and the dots that make up the image are basically invisible to the naked eye.
Aside from deciding if you want to print at the highest resolution, all the other settings should be used for the highest quality and these will unfortunately include the slowest speed.