What is a Pixel?
Digital photographs (sometimes called a raster
images or Bitmaps) are comprised of thousands or
millions of Pixels (short for
Picture Elements) they are
the tiny building blocks of a digital photo, the smallest
square/rectangular dot of colour found in the image.
Resolution
When talking about resolution, it refers to how many pixels are in the
digital photograph, for example, 50x50 resolution is a low resolution,
whereas, 5000 x 5000 pixels is a high resolution. The higher the
resolution, the clearer the picture is, however having a higher picture
resolution than is necessary does not serve any purpose.
Monitor Resolution
Generally speaking computer monitors aren't very sharp at displaying
images in comparison with print. For optimum sharpness on a computer
monitors, images should be displayed at 72 dpi (pixel dots per inch). If a
digital photo has a pixel size of 900 x 600dpi, then it will can be viewed
at maximum clarity on screen at 12.5" x 8.3" (317x210mm)
Print Resolution
For optimum sharpness on the printing press, images have to be displayed
at 300 dpi (dots per inch). If a digital photo has a pixel size of 900 x
600ppi, then it will can be viewed at maximum clarity on paper at 3" x 2 "
(76 x 51mm) - see below
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900 pixels ÷
300ppi = 3" (76mm) wide
600 pixels ÷ 300ppi = 2" (51mm) high
If for example you
were to prepare an image for the print press at A4 sheet size (210 x
297mm) - at 300 dpi then it would need an resolution of
3507 pixels high x
2480 pixels wide.
(excluding bleed)
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