Color camera returns gray image

[KGB0507]

When I try to display the frames received from the camera using OpenCV, I find that they are grayscale, even though the camera is color. How can I convert the received frame to a color image (yuyv422p format)?

[Speykious]

Sorry for not responding for so long. Could you be more specific?
Also, you said "using OpenCV". Do you mean that you're using it to display the frames you received from SeeShark, or that you're using it instead of SeeShark? If that's the case then it wouldn't be an issue with SeeShark...
If you're using SeeShark, have you checked the input formats available for your camera?

[KGB0507]

I use OpenCV to display and save frames received from SeeShark.
Here is the sequence of my actions (first 7 are the original from your samples):

1. Call SetupFFmpeg()
2. Create CameraManager and declare CameraInfo
3. Display available cameras and select the desired one by index, initialize CameraInfo by assigning manager.Devices[index];
4. Declare VideoInputOptions
5. Display available VideoInputOptions and select the desired one by index, initialize VideoInputOptions by assigning device.AvailableVideoInputOptions[index];
6. Initialize Camera by assigning manager.GetDevice(device, vios);
7. Subscribe to receive frames (karen.OnFrame event)
8. In the event handler: select the format

create OpenCV Mat from the data and save

I know for sure that the camera which I used can produce both grayscale and color images.

[Speykious]

Have you tried outputting your raw frames first to make sure the problem wasn't with OpenCV?
For example, take the SeeShark.Example.Stats as a baseline and output all raw frames received in the frame handler into a single file, then use FFmpeg to turn it into a video like this:

ffmpeg -f rawvideo -video_size ${WIDTH}x${HEIGHT} -pixel_format yuyv422p -i $YOUR_RAW_IMAGES_FILE camera-feed.mp4

[Speykious]

Actually, different questions:

• What formats does SeeShark say are available? Are they all correct or are there some that are missing?
• Which one did you choose?
• What's the format of the frames you receive after that?

[KGB0507]

Have you tried outputting your raw frames first to make sure the problem wasn't with OpenCV? For example, take the SeeShark.Example.Stats as a baseline and output all raw frames received in the frame handler into a single file, then use FFmpeg to turn it into a video like this:

ffmpeg -f rawvideo -video_size ${WIDTH}x${HEIGHT} -pixel_format yuyv422p -i $YOUR_RAW_IMAGES_FILE camera-feed.mp4

I tried to select different video input options and write received frames into file (if I undestood you correctly, I wrote every frame using BinaryWriter.Write(frame.RawData)). But the problem is that RawData arrays have the length of multiplied width and height with one channel. So the only way that was successful was to choose "-pixel_format gray" in ffmpeg conversion.
So there are available video input options:

I have tried most of them (both mjpeg and yuyv422), but the result is the same: I receive only gray images from SeeShark. Even the length of RawData array is the same (frame.Width * frame.Height * 1).
But this camera is color and supports 16 bpp (bits per pixel) and 24 bpp formats (we get color images using standard Windows application "Camera" and get available image formats through AccordNet library), it should give color frames.

[Speykious]

I see. Very weird indeed. Do you have any logs from FFmpeg while using SeeShark? If not, could you try again with them, for example FFmpegLogLevel.Verbose?

[KGB0507]

Well, there are logs from FFmpeg after choosing option #25 yuyv422 (800, 600) - 20,000 fps:
*Info, Quiet, SkipRepeated, Warning, Panic, Fatal, Error: nothing
*MaxOffset:

*Trace:

*Debug:

*Verbose:

[Speykious]

Thank you; I guess the Debug level is best here.
One thing that's immediately noticeable is that you're telling me you chose a yuyv422 option, but the logs are showing calls to the mjpeg decoder instead. Did you mix up your options? If not then FFmpeg is somehow overwriting your choice...

One additional thing to try is to see if FFmpeg itself is the cause of this. Here's how you can figure this out:

• enumerate your devices with ffmpeg -f dshow -list_devices true -i dummy
• list your device's options with ffmpeg -f dshow -list_options true -i video="Your Camera Here"
• look at your camera with one of these commands:
  • using yuyv422: ffplay -f dshow -video_size 800x600 -framerate 20 -pixel_format yuyv422 -i video="Your Camera Here"
  • using mjpeg: ffplay -f dshow -video_size 800x600 -framerate 20 -vcodec mjpeg -i video="Your Camera Here"

Make sure to use ffmpeg 5.1.2. You can get the Windows build here if you haven't already.

In any case, I'm starting to run out of ability to help, given how weird this issue is. But I might be able to figure out something better on a call. If that's ok with you, I just created a Discord server for additional support.

[KGB0507]

It's a really interesting phenomenon, but I haven't changed my settings and have always chosen the 'yuyv422' option. So FFmpeg's behaviour is strange to me too.
I have tried all the commands you suggested, so there are results:
*mjpeg:

*yuyv422:

I actually use FFmpeg 5.1.2.

[Speykious]

• For the mjpeg option, do you see your image in gray or is it colored normally?
• Can I see the output of ffmpeg -f dshow -list_options true -i video="Global Shutter Camera"?