Images                                                                         

 

 

Learning perspective The two sides of the brain have different attributes and respond to different stimuli. The left is analytical, verbal, sequential and linear; the right is visual, spatial, holistic and relational. It follows that the left is more logical, responding better to textual material, whilst the right is more imaginative, responding to images. If the right side is not stimulated, it is harder for students to put ideas into context. Studies have shown that the use of relevant images can increase a student's comprehension of new material as well as promoting interest. Images are generally more evocative than words and more precise in triggering a wide range of associations.

Images have a key advantage over textual content: an individual's response to an image will be described in their own words. By absorbing the information and recording it in a way that makes sense to them, students will increase their understanding and recollection of a concept. By establishing a balance between the use of images and the use of words, educators can increase the learning potential of their students.

Image relevance The direct relevance of an image to what is being read or heard is vital. Because sight is the most receptive sense for most people, an obscure or irrelevant image will distract from other messages being given. If there is an image that is relevant to the information of a particular screen, insert it. If you can replace text with an image, do so.

Simple representations should not be discounted because they are not 'sophisticated' enough. Can the image be simplified without losing the point? If so, simplify it.  Pictures not covered by the information in the text will not enhance the learning of the text, on the contrary. For each screen with an image, what is the intended purpose of that image? If it does not have a purpose relevant to the text, remove it.

Different images require different selection criteria. Instructional images have been classified into three types, on the basis of how they convey meaning:

    • Representational : those pictures that share a physical resemblance to the concept being portrayed. For example, photographs. Representational images must faithfully represent the original image

representational image

Representational image of a fish swim bladder

    • Analogical : those pictures that explain a concept by showing a similar example and drawing a comparison between the two. Analogical images only work if the analogy supports the textual content and vice versa. It helps if the analogy is self-explanatory.

analogical image

Analogical image: principle of a submarine as illustration to the functioning of a swim bladder

    • Logical : those pictures that show logical representations of the physical concepts being represented. For example, flow charts, graphs and charts. Logical images that do not simplify the figures or concepts they represent are superfluous.

logical images

Logical image: schematical representation of the physical laws involved in buoyance by swim bladder inflation

 

Image quality Carefully select the image with its background. A white (or clear) background for a black image is not the most successful for projection because the bright light is tiring on the eyes. Either a yellow background for a black image or a dark blue background for a white or yellow image is preferable.

Consider the shape, size and spacing of letters. A bold, simple and lower case lettering style is most legible. Omit distracting detail and include selective emphasis. The gradual revelation of details will facilitate an explanation and allow for a greater amount of visual information to be presented.

Cropping and re-sizing Cropping refers to the removal of the outer parts of an image to improve framing, accentuate subject matter or change aspect ratio.

before cropping

Original image

Cropped and re-sized image. The focus is now more clearly on the subject (a Tilapia).

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Technical issues 

Common concepts

Resolution The display resolution of a digital television or computer display typically refers to the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is controlled by all different factors in cathode ray tube (CRT) and flat panel or projection displays using fixed picture-element (pixel) arrays.
The figure below illustrates the effect of increasing resolution (expressed as pixel x pixel) on the quality of an image.

resolution

Pixels: (PIcture ELement) is the smallest piece of information in an image. Pixels are normally arranged in a regular 2-dimensional grid, and are often represented using dots or squares. The intensity of each pixel is variable; in color systems, each pixel has typically three or four components such as red, green, and blue, or cyan, magenta, yellow, and black. (Wikipedia).

DPI:  Dots per inch is a measure of spatial printing or video resolution, in particular the number of individual dots or pixels within the span of one linear inch (2.54 cm.)

Compression & File formats

JPEG: commonly used method of compression for photographic images. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10 to 1 compression with little perceivable loss in image quality.

  • The JPEG compression algorithm is at its best on photographs and paintings of realistic scenes with smooth variations of tone and color. For web usage in particular, where the bandwidth used by an image is important, JPEG is the ideal photographic image format.
  • On the other hand, JPEG is not as well suited for line drawings and other textual or iconic graphics, where the sharp contrasts between adjacent pixels cause noticeable artifacts. Such images are better saved in TIFF format (for local usage) or in GIF or PNG format (for web usage).
  • JPEG is also not well suited to files that will undergo multiple edits, as some image quality will usually be lost each time the image is decompressed and recompressed (generation loss). It is preferable to use a non-lossy format such as TIFF while working on an image, with the final image saved as JPEG after all editing is complete. (www.jpeg.org )

GIF: The Graphics Interchange Format (GIF) is an 8-bit-per-pixel bitmap image format. also supports animations and allows a separate palette of 256 colors for each frame. The color limitation makes the GIF format unsuitable for reproducing color photographs and other images with continuous color, but it is well-suited for more simple images such as graphics or logos with solid areas of color.

  • GIFs are suitable for sharp-edged line art (such as logos) with a limited number of colors. This takes advantage of the format's lossless compression which preserves very sharp edges (in contrast to JPEG).
  • GIFs are used for small animations and low-resolution film clips.
  • In view of the general limitation on the GIF image palette to 256 colors, JPEG is a more commonly used format for digital photographs. JPEGs can save information on more than 16 million different colors and use more aggressive lossy compression which has a less noticeable effect on photographs than it does on images with sharp edges.
  • The PNG format is a popular alternative to GIF images since it uses better compression techniques and does not have a limit of 256 colors, but PNGs do not support animations.

TIFF: Tagged Image File Format is a file format for storing images, including photographs and line art.

PNG: Portable Network Graphics (PNG) is a bitmapped image format that employs lossless data compression.

Bitmap: The BMP file format, sometimes called bitmap or DIB file format (for device-independent bitmap), is an image file format used to store bitmap digital images, especially on Microsoft Windows and OS/2 operating systems. The simplicity of the BMP file format, and its widespread familiarity in Windows and elsewhere, as well as the fact that this format is relatively well documented and free of patents, makes it a very common format that image processing programs from many operating systems can read and write. While most BMP files have a relatively large file size due to lack of any compression, many BMP files can be considerably compressed with lossless data compression algorithms such as ZIP because they contain redundant data.

 

Characteristics of the various compression types

FORMAT
Losless Compression 
Raster / Vector
Color depth
Trans­parency
Meta­data
Multi-page
Animation
Layers
GIF
Raster
1, 2, 3, 4, 5, 6, 7, 8
Yes
Yes
Yes
Yes
Yes
JPEG
Lossy & Lossless
Raster
8-bit (greyscale), 12-bit, 24-bit
No
Yes
No
No
No
PNG
Lossless
Raster
1, 2, 4, 8, 16, 24, 32, 48, 64
Yes
Yes
No
No
No
TIFF
Losless
Raster & Vector
1, 2, 4, 8, 16, 24, 32
Yes
Yes
Yes
No
Yes
Windows bitmap
Losless
Raster
1, 4, 8, 16, 24, 32
Yes
Yes
No
No
No

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Finding, sharing, storing and using images

The possibilities for incorporating visual elements in learning activities today are boundless. Images in every subject imaginable are readily available. Thanks to many free websites, finding, sharing, storing and organizing images are made easy. As a user, you can search for Creative Commons registered images that you know can be used with few restrictions, you can store your own photos and decide who can see them (whether they are solely for your own viewing, open to chosen groups or open to the general public), and you can create a class site and encourage students to contribute their own images.

Watch this video “Online photo sharing in Plain English”:

 

 

There are many sites where you can find, store and share images. If you want to use images on these sites, be  sure to check copyright information. The safest is search for Creative Commons registered images so you have a clear idea of how you can use the images.

Here are sites where you can store, find and share images:

images.google.com :  comprehensive image search  

www.flickr.com : online photo management and sharing application  

picasa.google.com : find, organize and share your photos  

www.smugmug.com : easy, ad-free photo-sharing  

www.zooomr.com : store & share image and video. Specifically supports mobile devices.  

www.snapfish.com : store & share photos. Make personalized photo albums (by HP).  

photobucket.com : store & share photo & video. Make slideshows.  

www.shutterfly.com : store & share pictures. Edit pictures online.  

www.imageshack.us : store & share images, flash files and movies.  

www.webshots.com : store & share pictures and video's.  

www.myalbum.com : store & share pictures. Make albums.  

www.woophy.com : Store & share pictures. Pictures are visually represented on a world map  

 

Specific academic purposes:  

seafood.ucdavis.edu/organize/images.htm : list of useful links to academic sites featuring images

www.bioscience.heacademy.ac.uk/imagebank : image database by the UK Centre for Bioscience 

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What is Flickr and how can I use it?

Flickr is the largest of the photo sharing sites and the one we would suggest that you try.

 

 

And the best way to learn what Flickr is all about is to go to the site, create an account and upload some of your photos. This video gives you good instructions on how to start:

 

 

As mentioned, it is possible to create and join different groups in Flickr. (http://www.flickr.com/help/groups/#57) We have created a group for aqua-tnet, which you can find here:

http://www.flickr.com/groups/aqua-tnet/ 

Please join the group and begin uploading your  images to share with colleagues.

Frequently Asked Questions If you have any questions, Flickr has a fairly comprehensive FAQ at http://www.flickr.com/help/faq/

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