Post Processing and Effects
Key Vocabulary to Remember
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Introduction
Image editing involves a vast array of techniques aimed at making pictures better fit your expectations, use for artistic or illustration purposes, and much less frequently as a result of publishing medium requirements.
Post processing refers to extensive editing that severely alters the original image. It can involve adding a transparency layer to a standard picture and even be as extensive as removing certain objects and features shown in the original picture.
Adding transparency
No photography ever has transparency by itself, no matter how well it looks. The camera can only make a better or a worse initial picture that showcases a product in a particular background. Even lighting and various techniques may make it seem that the product is neatly placed in front of an invisible background, but it still has no transparency. True transparency is achieved as part of an extensive editing of the initial picture, taking quite an extensive amount of time to reach good results, particularly when the initial image is complex or has an unevenly lit subject.
In order to add transparency you need advanced editing software such as the freely available Gimp and Krita, or commercial one such as Adobe Photoshop. In the process of adding transparency you will split your initial image in two layers, one will be the background, empty, the other one will hold the actual picture you will edit. This is the easiest and most versatile approach to editing. As you remove parts of the upper layered picture, the background will be more noticeable, until it will fully take all the space outside your subject.
The process of removing image pixels outside the boundaries of your subject may seem logical, but no application can make the same guesses as you in terms of how to interpret the parts of the image that should be discarded. Using the typical "magic wand" tool to select the outer area to delete may work on highly continuous areas and in excellent light conditions, as the algorithm has little issues in deciding what seems as background. However, in more than 90% of original pictures, this is hardly the case, you have to use another method to carry on your task.
The most likely way of achieving a good transparency is simply to draw an outline that selects the area that should be discarded. This involves using tools such as the "lasso" to carefully select points that should be marked as the edge of your subject, and drawing this outline slowly, step by step, around the picture, with a zoomed-in picture and having an extremely steady hand. It is better to select smaller areas to later remove as this reduces the chance of an unsteady click ruining your 5 or ten minutes careful tracing of the edges. Instead of using a lasso you may draw a filled polygon, which has the additional advantage of being less likely to suffer from the risk of not undoing your last missed step. This polygon will be ended either very close to the last step of your tracing, or exactly at that final point.
I generally suggest you not closing the polygon on the first point you draw of that outline, as it would offer the chance of creating additional sides to id that extend from the outline until each edge of the picture. In this way, a very large area can be covered and deleted in one go, when the polygon is selected and removed. This would create a clear outline that is very easy to evaluate. If the outline is not to your liking, you can undo a single step and attempt to change some of the polygon side intersection points, altering easily your process. When the polygon and subsequent removal of the area painted over is carried out, you are left only with a small sticking part of the original picture that can be easily selected using a basic rectangular selection tool and subsequently removed.
The final result of the process is an original image layer that has a cutout, where all the image information that stands beyond this edge is marked specifically as having no content. This resulting image cannot be used as is, since the format used by the program is different than the one of your publishing medium. To achieve usable image files you need to export this picture into a format that holds transparency information, or the so-called alpha-channel. A common, modern format is PNG, that also offers slightly smaller files, without affecting image quality. Subsequent editing while maintaining the PNG format also has the additional advantage of portability beyond accuracy, as all the original information is well retained and possible to edit in just about any software. Exporting is quite well managed by most software information, being assumed that your image should contain all your original layers. In case this option is not well considered by default, you can specify it when asked by the program.
Advanced effects
Complex effects may be applied to images