Image Analyzer questions

Zheng,

Zheng Zhao said:

In "properties" of Image Analyzer the last field is "Read data as", and there are three options to select from

1. 8 bit data
2. 16 bit data
3. 32 bit data

What do these options mean? For a typical BT.656 input whose data stream arrangement is U-Y-V-Y, the number of pixels to skip to get the next value (Y stride) has already been set per CCS4 help's instruction together with other fields, and I was able to get the captured image displayed. The value of Y stride is set to 2 bytes, U and V stride both to 4 bytes, then why do we still need this "read data as"? What is its function?

Although I still need to confirm this, usually the "read data as" option indicates how the analyzer will increment the data address read from the device memory - if the minimum addressable unit on the device is an 8-bit byte, then each address increment will read a single byte and assemble the image according to the previous parameters. However, some devices have 16-bit minimum addressable unit, therefore this setting must be set appropriately.

Zheng Zhao said:

                      

Another problem is that although I was able to get video of fairly good quality in the VPBE end (display), the picture Image Analyzer displayed is largely green (please see the picture). Why does this happen? How to correct this?

When an image is shown correctly but with the wrong colors is usually because the color masks are wrong. Check how they were applied in the generated image.

Regards,

Rafael

Dear Rafael,

I did some experiments and it seems that 1) YUV mask 2) "Read data as", together overrides the setting YUV order.

The data stream is an BT.656 output from TVP5150 and the byte order, according to 5150 manual, is U-Y-V-Y. The scene in front of the camera is a colorful illustration page in Illustrated Oxford Dictionary featuring flowers of different colors.

Because of the 5150 output (U-Y-U-V four bytes group repetition), I set

1. Y mask: 0xFF00FF00 (0xFF00 also works)
2. U mask: 0x000000FF
3. V mask: 0x00FF0000

and "Read data as" is set to 32 bit data. Under this configuration the image is correctly displayed.

"YUV order" DOES NOT seem to have any effect here. With the above setting unchanged, whatever "YUV order" option (UYVY, YUYV, VYUY, YVYU) I select the image displayed is always the same.

The effect of changing "Read data order" is
When set to "16 bit data", Image Analyzer displays greenish image.

                              
When set to "8 bit data", Image Analyzer displays an image with gray background and flower in color close to purple.

YUV mask also has impact on the displayed image. There are a variety of combinations that YUV masks can be changed, however only one case is show here: When U and V mask bit order are swapped from the above correct setting

1. U mask: 0x00FF0000
2. V mask: 0x000000FF

 There is a heavy tint of blue in the displayed image.

The above are some experimental results. But if 1) YUV mask 2) "Read data as" together do determine the display mode, why "YUV order" option is still provided here? What is its purpose and functionality?

Sincerely,
Zheng