Comet Labs WN591 Manual de usuario descargar pdf (Pagina 40)

Help! There is a comet in my computer! 37

on the right side. In the image with severe shading (Figure 22D: 1-5), the background is

clearly much brighter in the lower left part of the image than in the upper right part.

Figure 22. Detection of image shading in Photoshop. Two cases are shown: an image with a low

level of shading (A, B) and an image with severe shading (C, D). The analysed images are

indicated with a red border. Images with shading have a wider peak of background grey values in

the histogram of image grey values (C) than images without shading (A; “Levels” tool in

Photoshop). Using the “Threshold” tool of Photoshop, as the slider for threshold grey values is

dragged from 255 (white) to 0 (black), the background is gradually revealed. Several successive

steps of this procedure are indicated with numbers 1-5 in B and D (decreasing threshold grey

values). See text for explanation.

1 2 ... 35 36 37 38 39 40 41 42 43 44 45 ... 48 49

Sin comentarios

Comet Labs WN591 Manual de usuario Pagina 40