Silver retention techniques have been developed to “create a distinguishing visual style” for some photographers. Some labs refer to the technique as silver retention, bleach bypass, or skip bleach. In all of these processes, varying amounts of silver are left in the print or negative film stock. And, no matter what it is called, the end results are very similar.
The two characteristics of Image Structure are grain and sharpness. There are two ways of evaluating these characteristics –subjectively (by looking at them) and objectively (by measuring them with a suitable instrument). It’s rather like the way we look at the tones and contrast of an image, and measure them with a densitometer.