Digital Imaging | Notes from Readings
File Types | Week 1
Raster Images
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Made up of a set of grid dots (pixels) where each pixel is assigned a color
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Resolution dependent
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When you transform, you stretch the individual pixels, making the image blurry
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Typically used for photographs, digital artwork, web graphics
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Can be saved in CMYK or RGB
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Either Lossy or Lossless
CMYK vs RGB
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CMYK is a four color printing process (cyan, magenta, yellow, and key [black])
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The colors represent the four inks that combine during the printing process
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Files saved in CMYK are optimized for physical printing
RGB is light based color (red, green, blue)
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The three primary colors of light that combine to produce other colors
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Files saved in this formal will be optimized for anything that appears on a
screen
Lossy vs Lossless
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Lossless images capture all the data of the original file
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File may still be compressed
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Will be able to reconstruct image to its original state
Lossy images approximate what the original image looks like
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Could reduce the amount of colors or analyze the image for any
unnecessary data
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Reduce file size, but also reduces image quality
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Ideal for online where file size and download speed are vital
JPEG/JPG
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A lossy raster format
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Stands for Joint Photographic Experts Group
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Most widely used formats online
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Have a sliding scale of compression that decreases file size but increases artifacts
or pixelation the more the image is compressed
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Should be used when
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Working with online photos and/or artwork
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Want to print photos and/or artwork
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Need a quick preview image
Don’t use when
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You need a graphic with transparency
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You need a layered, editable image
GIF
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Lossless raster format
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Stands for Graphics Interchange Format
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Widely used in web images, typically for animated graphics
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Can be exported in customized settings that reduce the amount of colors and
image information
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PNG
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You should used a GIF when
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Creating web animation
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You need transparency
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You need a small file
Don’t use a GIF when
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Need a photographic quality image
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You need to print an image
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You need a layered, editable image