A Guide to Digital Graphics


The following is a list of different file types in conjunction with Photoshop, explaining a bit about what they do as well as their pros and cons,

PSD:
A baseline Photoshop document that you can keep editing, not an actual image file.
JPEG:
Basic online image, exchanges quality for a smaller file size.
PNG:
Opposite to a JPEG, but maintains the same structure. Keeps the quality high, but also expands the file size as a result.
GIF:
Animated picture for the internet, loses a great deal of quality unless its boosted, ramping up the file size.
TIFF:
The same as a PNG, with the added bonus that you can save your layers with them in Photoshop.
EPS:
Another photo file but with lots of techno-babble added onto it, not for anyone who doesn't understand it at first glance.
PDF:
An executable file, mainly used to represent documents that aren't from word. Needs a special reader to activate, Adobe Reader being the most common one.
BMP:
A "Bitmap" file, basically just another image file, but it does it independent of the display divide (Windows, iOS) used.

Compression:

Image compression is minimising the file size of an image. Using formulas, the program throws away some colours in the image that's saved. This means less information, meaning a smaller file size.

It can be useful for when we want to save a lot of files, when we want to e-mail test images or for when saving to the web. It should be avoided however for when we wish to print images.

There are two types to compression:

Lossy - Throws out information to give a very small file size. Examples of these types of files are JPEG and GIF. Its should be noted that when saving a JPEG file in Photoshop, you can adjust the amount of compression that occurs, changing from very light compression to heavy compression.

Lossless - Image loses no quality but file sizes get bigger. Examples stem from PNG, PSD, EPS.

There are also TIFF files, which use no compression at all but create massive files because of it. They are mainly useful for Print Documents and photo files that you may want to edit later.

Colour Space

Colour space (Otherwise known as Colour profile or Colour mode), is the range of colours a device can recognise. They each differ from device to device, such as the number of colours a printer can print, or the number of colours a computer screen can reproduce.

For printing in Photoshop, we should use the CYMK colour space. CYMK stands for Cyan, Magenta, Yellow and Key (Black), as they are the four colours most printers use to recreate images.

For the Web, we use the RGB colour space. RGB clearly stands for Red Green Blue, as a computer monitor combines these three colours to recreate a whole range of other colours. If you get close enough to a screen, you can actually see this in action.

Less colours in the Colour Spectrum are available in the CMYK colour space meaning that images made for print may appear less vivid than those prepared for screen.

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