I've recenly been getting more into Abstract photography, and am working on a new talk on this subject. Abstract art can be hard to define. In photography I consider an image abstract if the meaning or content is less important than visual qualities such as shapes, colours, lines and textures. That does not mean that you cannot tell what the image is or what the object is made of (e.g. peeling paint on a wooden door).
There are many potential subjects for abstract photography. In many cases it is a matter of looking closely and seeing a small part of a scene which can work as a composition. There is an overlap with intimate landscapes, athough in many cases the subject of the latter is at least as important as the abstract qualities.
Many techniques can be used for capturing abstract photos. For example they may be 'straight' shots, multiple exposures, composites, collages, or the result of intentional camera movement (ICM).
The subject of the image can be broadly categoried as natural or artificial, and that is how I have divided the images below.