Using QOI with LUCID Cameras

Quite OK Image Format (QOI) is a lossless image compression method that balances compression ratio and throughput. This article explains how to obtain a compressed image from a camera and how to decompress the image.

Prerequisites

Phoenix camera with firmware v1.78 and higher
Triton camera with firmware v1.127 and higher
Arena SDK v1.0.49.3 and higher

The following cameras do not support QOI:

Phoenix: PHX050S-P, PHX050S-Q, PHX050S1-P, PHX050S1-Q, Phoenix Dual Extended-Head cameras
Triton: TRI050S-P, TRI050S-Q, TRI050S1-P, TRI050S1-Q, TRI02KA-M, TRI054S-C, TDR054S-C

How to enable QOI compression on your camera

Stop streaming if the camera is streaming images
Set Pixel Format to a QOI pixel format
- Mono cameras: QOI_Mono
- Color cameras: QOI_BayerRG8, QOI_Mono8, QOI_RGB8, QOI_BGR8, QOI_YCbCr8
Set Acquisition Frame Rate Link Limit Enable = False.
Set ISP Clock Speed = Fast.

Comparison

Example settings with a TRI032S-M and resulting change in frame rate are shown below.

QOI works best on a controlled scene. The compression ratio and compression speed can vary. Longer compression times result in slower framerates.

Using Arena SDK to grab a QOI-compressed image

C++

Arena::SetNodeValue<<bool>(pDevice->GetNodeMap(), "AcquisitionFrameRateLinkLimitEnable", false);
Arena::SetNodeValue<GenICam::gcstring>(pDevice->GetNodeMap(), "ISPClockSpeed", "Fast");
Arena::SetNodeValue<GenICam::gcstring>(pDevice->GetNodeMap(), "PixelFormat", "QOI_Mono8");
 
pDevice->StartStream();

Arena::ICompressedImage* pCompressedImage = pDevice->GetCompressedImage(2000);

// use compressed image
pDevice->RequeueBuffer(pCompressedImage);

pDevice->StopStream();

See the following code samples, which are available with the Arena SDK or the Arena Python Package:

Cpp_Acquisition_CompressedImageHandling
Cs_Acquisition_CompressedImageHandling
C_Acquisition_CompressedImageHandling
py_acquisition_compressed_image_handling.py and py_acquisition_compressed_image_handling.ipynb

Using Arena SDK to decompress a QOI-compressed image:

C++

IImage* pDecompressedImage = Arena::ImageFactory::DecompressImage(pCompressedImage);
 
Arena::ImageFactory::Destroy(pDecompressedImage);

See the following code samples, which are available with the Arena SDK or the Arena Python Package:

Cpp_Acquisition_CompressedImageLoading
Cs_Acquisition_CompressedImageLoading
C_Acquisition_CompressedImageLoading
py_acquisition_compressed_image_handling.py and py_acquisition_compressed_image_handling.ipynb

Decompressing a QOI-compressed image

C++

#define QOI_IMPLEMENTATION
#include "qoi.h"
[...]
 
Arena::SetNodeValue<<bool>(pDevice->GetNodeMap(), "AcquisitionFrameRateLinkLimitEnable", false);
Arena::SetNodeValue<GenICam::gcstring>(pDevice->GetNodeMap(), "ISPClockSpeed", "Fast");
Arena::SetNodeValue<GenICam::gcstring>(pDevice->GetNodeMap(), "PixelFormat", "QOI_Mono8");
 
pDevice->StartStream();
 
Arena::ICompressedImage* pCompressedImage = pDevice->GetCompressedImage(2000);
 
qoi_desc desc = { 0 };
void* decompressed_image = qoi_decode(pCompressedImage->GetData(), (int)pCompressedImage->GetSizeFilled(), &desc, 1);
 
QOI_FREE(decompressed_image)
 
pDevice->RequeueBuffer(pCompressedImage);

Arena SDK’s Arena::ImageFactory::DecompressImage decompresses images using the qoi_decode function, which works in the same way as the function shown above.

The following decompression algorithms are used:

Color images: https://github.com/phoboslab/qoi
Mono images: https://github.com/jstavats/qoi

Using a non-QOI pixel format with a QOI configuration

If you use a non-QOI pixel format with the QOI configuration described above, you could encounter dropped frames.

Example:

Pixel Format = Non-QOI pixel format
Acquisition Frame Rate Link Limit Enable = False
ISP Clock Speed = Fast

If the resulting bandwidth is beyond 1Gbps, you will encounter dropped frames on the host. The host is notified of these dropped frames with a “Frame Dropped” event.