Color Space and Format Selection
Picolo U4 H.264 PCI-104 is capable of delivering images either in RGB or in the YUV color spaces. with the following images formats:
Format |
Color Space |
Data packing |
Y8 |
YUV |
N/A |
YUV422 |
Packed |
|
YUV420PL |
Planar |
|
YUV422PL |
||
RGB15 |
RGB |
Packed |
RGB16 |
||
RGB24 |
||
RGB32 |
You can select the format through the Virtual File System API.
YUV Color Space
If a format of the YUV color space is selected, the pixel data is delivered using the YCbCr color space. The video formatter does not need to perform any color space transformation, and the output levels of Y, U, V components delivered are identical to the output levels of Y, Cb, Cr components delivered by the video decoder. No additional gamma correction is performed.
Output values of Y, Cb and Cr components for a "75% amplitude, 75% saturated YCbCr color bar" test pattern
Component |
Light gray |
Yellow |
Cyan |
Green |
Magenta |
Red |
Blue |
Black |
Y |
180 |
162 |
131 |
112 |
84 |
65 |
35 |
16 |
Cb (U) |
128 |
44 |
156 |
72 |
184 |
100 |
212 |
128 |
Cr (V) |
128 |
142 |
44 |
58 |
198 |
212 |
114 |
128 |
The above results are obtained under the following conditions.
- The Contrast setting must be nominal (100% luminance gain).
- The Brightness setting must be nominal (null luminance offset).
- The Saturation setting must be nominal (100% color saturation).
RGB Color Space
If a format of the RGB color space is selected, the pixel data is delivered using the RGB color space. The video formatter converts the ITU-R BT.601 digital YCbCr pixel data in a RGB pixel data using the following formulas.
R' = 1.164(Y - 16) + 1.596(Cr - 128)
G' = 1.164(Y - 16) - 0.813(Cr - 128) - 0.392(Cb - 128)
B' = 1.164(Y - 16) + 2.017(Cb - 128)
R', G', B' must be saturated at the 0 and 255 levels.
The output range of R, G, B components occupies the full digital range, as shown in the following table.
Output range of R, G, B components
Format |
Output code for black |
Output code for white |
RGB15 |
R = 0, G = 0, B = 0 |
R = 31, G = 31, B = 31 |
RGB16 |
R = 0, G = 0, B = 0 |
R = 31, G = 63, B = 31 |
RGB24 |
R = 0, G = 0, B = 0 |
R = 255, G = 255, B = 255 |
RGB32 |
R = 0, G = 0, B = 0 |
R = 255, G = 255, B = 255 |
No additional gamma correction is performed.
Output values of R, G, B components for a "75% amplitude, 75% saturated YCbCr color bar" test pattern
Component |
Light gray |
Yellow |
Cyan |
Green |
Magenta |
Red |
Blue |
Black |
R (Red) |
191 |
191 |
0 |
0 |
191 |
191 |
0 |
0 |
G (Green) |
191 |
191 |
191 |
191 |
0 |
0 |
0 |
0 |
B (Blue) |
191 |
0 |
191 |
0 |
191 |
0 |
191 |
0 |
The above results are obtained under the following conditions.
- The Contrast setting must be nominal (100% luminance gain).
- The Brightness setting must be nominal (null luminance offset).
- The Saturation setting must be nominal (100% color saturation).