One of the most common mistakes I have seen, in particular with corporate presentations, is images or photographs inserted with strange proportions.
Any visual object has a correct ratio of width to height, reflecting the original form in which the image was created or captured. However, when objects are inserted into powerpoint for example, and subsequently moved around, a common tendency is to just resize the image any which way, usually to satisfy space constraints or for respect of symmetry.
This in effect results in a design philosophy that has no respect for visual aesthetics, and one that also does not respect the original form of the object.
There are many ways to maintain correct ratio of proportions.
1. The simplest is to hold down SHIFT (Windows users) when resizing an image. In powerpoint and other MS Office tools, this will automatically resize the image width and height with the original ratio as a multiplier, leaving the integrity of the image intact.
2. In other desktop publishing programs, there is usually a check option (tick-box) that can be selected for the same effect.
3. In some professional desktop publishing programs, the automatic choice is to resize images while maintaining proportion. In these cases if you find that the proportion ratio of the image, the multiplier, does not allow you to resize an image for effective use within your document, then best practice is to continue to maintain proportions, but crop out some of the image so that you get a better size or better fit.




