How to find and process Internet Graphics for Classroom Use

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How to find and processInternet Graphicsfor
Classroom Use
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Visual World

• One picture is worth a thousand words.
• A good picture is a worth a thousand pictures but
  ...
• ... a good picture requires processing to be fit
  for a given purpose

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A lot of things can go wrong
bleak colours
low contrast
limited colours
blue tinge
blue tinge
blue tinge
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A lot of things can go wrong but a lot
can be improved.
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Overview of the workshop

• Find (an image)
• Optimize it
• Use it effectively

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Real (reverse) overview

• A bit of theory
• Processing
• Search engines and software
• Tips and tricks

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Theory key concepts

• Pixel
• Resolution
• Compression
• Color depth
• Vector vs raster graphics
• File formats

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Theory pixel 1
Magnified image pixels visible
Pixels are building blocks of an image.
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Theory pixel 2

• Information about each pixel in an image contains
  its detailed
• position in the picture (where to put the given
  pixel)
• precise colour description (how to build colour
  of the pixel)
• An average postcard size photograph contains
  more than 2 million pixels (1600x1200)
• The more pixels a given area has the better
  quality of the image is

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Theory resolution 1

• The level of detail an image holds
• Unit pixels/dots per inch

1 pixel per inch
2 pixels per inch
5 pixels per inch
The more pixels per inch the clearer the image
Source wikipedia.org
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Theory resolution 2
Resolution and quality
18 ppi
72 ppi
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Theory resolution 3

• Optimum resolution for computer screen is 96 ppi
  (presentation, web)
• Optimum resolution for computer printout is 150
  ppi (home printer)
• Optimum resolution for professional printing is
  300 ppi and up

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Theory compression

• Uncompressed high quality images take a lot of
  disk space (a single photograph about 10-25 MB)
• The process of compression reduces the amount of
  data by eliminating lengthy descriptions of the
  pixels one description is used for all
  identical pixels or ...
• ... eliminating the differences between pixels
  the eye wouldnt be able to see

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Theory compression types

• Lossless data compression algorithms that allow
  the exact original data to be reconstructed from
  the compressed data.
• Lossy data compression, which does not allow the
  exact original data to be reconstructed from the
  compressed data.

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Theory colour depth

• Scientific experiments have shown that the number
  of colours we can see range as high as 10
  million.
• Computers initially used 2, later 16, 256, 65 000
  and now use 16,7 mln colours.
• The number of colours influences file size

16196 colours
7 colours
90 kB
15 kB
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Vector vs raster graphics

• Raster image each point (pixel) of the image is
  described individually
• Vector image the sequences of points are
  defined by mathematical formulas

The red line is described by yx formula
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Vector vs raster graphics
raster
vector
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Why is all that so important?

• Number of pixels, resolution, compression, colour
  depth, type of graphics (raster/vector) determine
  the size and the quality of an image and its
  suitability for a given purpose

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File formats

• Uncompressed bmp, tif
• Compressed (lossless) gif, png
• Compressed (lossy) jpg
• Vector wmf, emf

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File formats - characteristics

• Bmp too big for comfortable use retains,
  however, all the important information
• Gif only up to 256 colors can be represented
  (good for simple geometrical shapes, text)
• Jpg full color (excellent for photographs)
• Wmf small but artificial looking

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File formats - characteristics

• Bmp too big for comfortable use retains,
  however, all the important information
• Gif only up to 256 colors can be represented
  (good for simple geometrical shapes, text)
• Jpg full color (excellent for photographs)
• Wmf small but artificial looking

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Basic processing using Irfan View

• Rotation
• Cropping
• Resizing/resampling
• Controlling color depth
• Improving contrast and saturation
• Enhancing colors
• Batch processing

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Where to look for good graphics

• Search engines http//www.google.com
  http//yotophoto.com
• Free stock photographs http//www.sxc.hu/http//
  www.freefoto.com/ http//www.morguefile.com/http
  //www.freephotosweb.com/
• http//office.microsoft.com/clipart

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Software free commercial

• Irfanview (free) (www.irfanview.com)
• Paint NET (free) (http//www.getpaint.net)
• Photofiltre (free) (http//www.photofiltre.com)
• GIMP (free) (www.gimp.org)
• Adobe Photoshop (Adobe Elements) (www.adobe.com)
• Corel Photopaint (www.corel.com)

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Powerpoint presentation too big

• Process graphics (size, resolution, colors)
• Save as gif/jpg files
• Insert into the presentation
• Link graphics instead of embedding it into the
  presentation (older Office software
• Steps 1-3 use capture

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Dog image

1. Go to www.google.com and type dog set search
   parameters
2. Good quality photograph go to www.sxc.hu
3. Vector image go to http//office.microsoft.com/cl
   ipart

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Only a part of an image is needed

1. Run Irfanview
2. Select the area you want to keep
3. Press Ctrl-Y
4. Save or copy image to buffer

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Too red, too pale, too dark

1. Run Irfanview
2. Press ShiftG (or go to Image/Enhance colors)
3. Change color balance
4. Save file

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Dark areas to be removed

1. Run Paint NET
2. Click Magic wand or Lasso select
3. Cut the unwanted parts

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Batch processing

1. Run Irfanview
2. Go to File/Batch conversion/rename
3. Set parameters and press Start

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Removing background in Powerpoint

1. Paste the image into PP
2. Click the image
3. In the image toolbar select Make area
   transparent

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Web browser saving protected images and flash
images

1. Find the image
2. Press Print screen key
3. Run Irfanview
4. Paste the captured screen
5. Edit (crop?) and save

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Thank you! andrzej.walczak_at_gfo.pl