Digital images should be evaluated with the same scrutiny as web sites, online journal articles, and any other information you find online.
Resolution:
Resolution largely dictates the clarity and quality of the image. Digital images are made up of hundreds of small dots called pixels (picture elements). The more pixels there are per inch (ppi) the higher the resolution and the better the image quality. High quality resolution for printing is 300 ppi, but 72 ppi is appropriate for display on a computer monitor. When downloading, an image 1024 pixels along the long edge is optimal for reproduction.
Image Formats
JPEG (.jpg): Many images are stored as JPEG files because this format allows files to be compressed to take up less space. Because JPEG files are small, they are easily transported (email, flashdrives, etc).
GIF (Graphics Interchange Format, .gif): Another popular file type found on the web. Gif images are widely used for graphics.
TIFF (Tagged Image File Format, .tif): saves an uncompressed digital reproduction. Therefore, it is recommended you originally save high-quality TIFFs and then create JPEGs for general use.
BMP: uncompressed proprietary Microsoft format.
Other formats include, but are not limited to PSD (Photo Shop Document), SVG, and RAW. Image software tends to allow conversion of one format to another.
Most papers, reports and thesis include images such as charts, diagrams, sometimes maps, etc.
To add any image to the text consider the following:
1. All images are referred to when added to the text as figures or fig + a number fig.2 fig.3 fig.4 etc.
2. Do not capitalize the word figure or fig.
3. Never use expressions as figure below or figure above.
4. It is recommended that you put the figure as close as possible to the text referencing it.
5. Figures numbering should be consecutive starting from 1 and onwards.
6. On the same line as the label and number, provide a descriptive title/ caption, as well as source information in the following format:
fig. #. descriptive title, image creator's first name; description or image title; name or title of the website; publisher or sponsor of the site; date of creation; medium of publication ("web"); date of access.