The smallest unit making up a raster file. They will vary in sizes depending upon resolution.
The color channels in a file. CMYK, RGB, Grayscale…etc. We mostly work in RGB.
Dots Per Inch. This is the term that is for the 4-color industry. It means the number of dots printed per linear inch. We technically do not print with dots so the term is not accurate on most of our printing equipment but is only for reference. Programs such as InDesign, Quark Express and other layout programs will display a DPI window on your print set up. Depending on the printer/imager that you have, your dpi for bitmap printing can range from 150 to 2800 or higher.
Pixel Per Inch.
The number of pixels in a linear inch. 300 ppi would refer to 300 pixels in a single file line, one inch long. This term is more accurate for producers of pixel based images for the print and reproduction equipment we use. For photo images, in general, the higher the pixel a camera captures, the higher the quality of your image, especially if you are going to enlarge an image and quality is very critical.
A continuous tone file such as Photoshop and scans. These files are made up of pixels whereas a vector file (like one from Adobe Illustrator) is not. An example of vector file usage would for generating cuts on a CNC Router or for a logo that needs to be enlarged significantly without losing print quality.
Photoshop Document. Sometimes called Photoshop Native. This is the only format that “layered” Photoshop files can be saved in. This would be helpful if you need us to work with your image to make color corrections and adjustments.
When a company is compliant it means that the color management of all devices have met the standards from the International Color Consortium, (ICC). This usually means that color profiles are created and applied with color management software to achieve the standard.
The amount of data in a given file. The higher the resolution the more data and the larger the file size in bytes. (A bit is a single numeric value, either ‘1’ or ‘0’, that encodes a single unit of digital information. A byte is a sequence of bits; usually eight bits equal one byte.) Normally, if we are printing a file that you want to optimally display as Fine Art, then we would like to get a file that is at the highest resolution and with the greatest pixels allowed.
To Res Up a file, that is to change its resolution, does NOT make a bad scan or low res file better, it just makes it bigger and softer. You sometimes can start to see “pixelation” or “Choppy” edges on you image. You cannot res-up a file and make it look better without doing a lot more work, such as sharpening and sometimes adding noise or grain. Sometimes even that doesn’t work. Photoshop has built in filters that help up-res files incrementally. That will help, but sometimes it’s a hit-and-miss situation that calls for proofing part of the image at the final size.
COMMON SIZES AND THEIR MB SIZE
When you double the resolution, (150 to 300), you increase the Mb size by 4 times. That is why the big difference between 150 and 300 dpi.
Ex: An 8×10 at 200% = 16×20, which has an area 4 times that of an 8×10.
Megabyte size of a file equals length in pixels X height in pixels X the number of channels (3 for RGB and 1 for Grayscale). To convert inches to pixels, multiply the inches dimensions by 25.4 (25.4mm to the inch) Resolution, (DPI), is based on the metric system. Res 40 actually means 40 pixels per mm, so multiply inches by 24.4 you can figure out pixel size. Do this for both dimensions and multiply both numbers together, then multiply that number by 1 or 3, depending on the color space. The answer is your megabyte size. Remember that one million bytes to the megabyte so count 6 places from the right to place the decimal point.
Ex: 4″x5″ at 300 dpi = ?Mb 4″x300 dpi = 1200 pixels, 5″x300 dpi = 1500 pixels, 1200×1500 = 1800000, 1800000 x 3 (rgb) = 5400000. Move he decimal 6 place from the right and you have the file size of 5.4 Mb.