Highlight image filter significantly improves optical character recognition on text images - Emerging Trends in Image Processing, Computer Vision, and Pattern Recognition - page 117

be tested again. The visual representation of the cases that meet the condition in Equation (9c)
is shown in Figure 12 .
FIGURE 12 Possible cases for the condition in Equation (9c) to be fulfilled.
3.3 Visual Results of Applying Highlight Filter on Images
Highlight image filter produces the results in Figure 13 . It can be seen how this filter detects
the edges of the characters and sharpens them (the best example would be “ALL CHANNELS”
image) and how it creates contrasting shadows behind the characters (the black shadows can
be best seen on white colored “Golf: Women's British Open” text in the image).
FIGURE 13 The visual effect of Highlight image filter.
Because of the shadows behind the sharpened edges of the characters and because of the
increased contrast of the edges, the characters appear to be highlighted in the filtered image (a
slightly 3D effect), which is the main visual effect of Highlight image filter.
3.4 Highlight Image Filter Program Code and Visual
Representation
Part of the C# code that corresponds to Highlight image filter is being listed in Code 1 . The
b ufer array stores the image representation, more exactly the Blue, Green, Red, and Alpha
components in this order for the first pixel, then the components for the second pixel in the
same order and so on for the rest of the pixels in the image.
CODE 1 Part of Highlight image filter's algorithm.
The visual representation of the algorithm is shown in Figure 14 . The six cases next to the
first if are the visual representation of the condition. In other words, if the condition in Equa-
tion (6c) is met, we will found ourselves in one of the six possible cases. So far for the rest of
Figure 14 , the possible cases that meet the conditions are shown next to the if -s and else -s,
as it is also in the case of the second if , for which its condition is represented visually by two
out of six possible cases.