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.

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.