Transcript Basic Digital Imaging

Basic Digital Imaging
For PE 266
Technology in HPER
2 Types of Computer Graphics

Raster Graphics - also known as Pixelbased (you “paint” with pixels)




Building blocks of images are pixels
 Pixels are tiny squares
AKA “painted” images or bitmapped images
Cameras and scanners capture images in
pixels
Vector Based (you “draw” objects with
vectors)


AKA “drawn” or “object-based” images
Images are “described” in mathematical terms
Comparison of image types


If you zoom in close on a pixel
based image you will be able to see
the pixels (you will see jagged
edges when you zoom in closely)
If you zoom in close on a vector
based image you will always see
smoothly drawn edges regardless of
how closely you zoom in
Comparison of image types


Pixel based images can be edited
one pixel at a time – individual
pixels can be edited
Vector based images are edited as a
whole object – you can’t erase part
of a vector image
Comparison of image types

Pixel based images are typically used for
photo-type images (from cameras and/or
scanners)



File sizes tend to be larger than vector based
images
File types are things like jpg, gif, bmp, & tiff
Vector based images are usually used for
line art and web pages



File sizes tend to be smaller than pixel based
images
Flash files are vector based
Vector images can be scaled to any size with
no loss of image quality
Issues when capturing images

One of the main issues is resolution



Resolution is the number of pixels
(usually expressed as width and
height)
More pixels means better quality (and
larger size), but it also means larger
file sizes
Larger file sizes mean it will take longer
to work with and also to display on a
web page
More on resolution


Images are always captured in
pixels per inch although it is often
mislabeled as dots per inch (or DPI)
DPI is actually used to describe the
resolution for outputting images –
normally to a printer
Guidelines


Always capture images in higher
resolution than you ultimately will
need (if possible).
After capturing images process
them to get the desired final image
Basic image processing





Archive your original image (as raw,
tif, or png file) and work on a copy.
First crop your image
Then size and if necessary resample your image
Adjust levels
Compress and export image
Digital Imaging Assignment



Acquire 2 images – one from a
camera and one from a scanner
Process/optimize both images for
web page
Create graphic with Fireworks and
export it as a gif
Turn in the following:




3 files should be turned in (and the file
names should identify which is which)
Both processed images – one from
camera and one from a scanner (.jpg)
Gif file created in Fireworks
Assignment can be turned in through
e-mail or on USB storage device