Resolution

• Pixels
  Resolution
  Vectors and Bitmaps
  For Printing

What is a Pixel?
An image size is said to be for example 150*400 pixels, this means that we have 150 pixels in width and 400 pixels in height
A pixel is the smallest part that makes up a picture, in the image below this is an image of a very small circle that was magnified 3200%, you can see that edges are not smooth, these small squares are called pixels, pixels can be squares, dots, lines… depending on the software

Resolution
-Resolution: is the number of pixels in one measurement unit (mostly a1 inch square), Resolution is sometimes represented in ppi which means (pixels per inch)
The more pixels in one inch is the higher the resolution and the better the quality, but of course this will increase the file size.
-So, what is the best resolution? well, that depends on the purpose of your image. If your image will stay a digital copy 72 ppi is good, but if you are going to copy your image to a hardcopy (paper) this will depend on your printers type and dpi (dot per inch). But mostly you should stick to a high resolution like 300 or above.

Vectors and Bitmaps
-Vector drawing softwares like “illustrator” “Corel draw” and “flash” use mathematical equations of points, lines, curves and polygons to represent a graphic.
When the computer wants to repaint these graphics it goes back to these equations and see where they must be applied (the x and y axis) and re-draw the shape.
So, when you resize the graphic it does not get blurred or corrupted cause the equations are the same, the only difference is the x's and y's.
-In bitmap drawing softwares like “Photoshop” and “Microsoft paint”, the graphic is represented by pixels: each pixel has a position and color that is represented in a table that is mapped to (hence the name-bitmap) when you magnify the image it does not know what to do with the extra pixels, so it tries to guess what it should fill these extra pixels with and it copies from the pixels around it.
-Note : vector based drawing files are smaller in size since it doesn’t store every pixel representation

For Printing
-When you look closely at your printers model you will see something like (600dpi) = (600 dots per inch)
-When you create your Photoshop file make the ppi of it greater than 600 to get a good quality.
-This can be done in the image size popup menu (Images>> Image Size) or it can be done automatically (click on Auto and in the screen field  insert the lip (line per inch) then choose Good or Best)
-Just so that you know and to do it manually if you want
*Good means that the number you entered in the screen field, will be multiplied by 1.5
*Best means that the number was multiplied by 2.
*Draft will always give you a resolution of 72 no matter what the number is in the screen field.