By default the Scandit SDK is optimized for real-time video streaming. In general, barcodes in the image will not be decoded in every frame. Instead the engine tries to skip bad frames to meet real-time processing constraints.

Single image processing use-cases, e.g. scanning a scanned or photographed document, require a specific setup.

General Recommendations

Use a YUV or Grayscale image input format. RGB formats will be converted internally leading to a slower execution.
Use an image resolution between 800x600 to 1920x1080. 1280x720 is recommended.
Make sure to have an area of at least 320x160 pixels when setting a restricted code location area for barcode localization.
Having SIMD CPU support (NEON or SSE) improves execution times.
Pre-cropping the image is not required. The SDK can find the barcodes in the image.
Pre-processing (filter, blur, binarize) the image is not recommended. Provide natural images.
Very long codes require adjusting the enabled symbol counts in the symbology settings.
Blurry decoding using a custom camera and camera lens will not perform as well as high-end iOS or Android devices. Please contact us if specific optimizations for your camera are desired.

Video Streaming Use-Case

To achieve comparable results as the high level Data Capture API, you have to create barcode specific camera control algorithms that adjust exposure and auto-focus. The ScCamera implementations currently provided do not implement this.

For scenarios where a hand held device is used to scan a single barcode, the barcode scanner preset SC_PRESET_SINGLE_CODE_HAND_HELD should be set. Among other optimizations, this preset enables Smart Scan Intention, which prevents scans in the background or during fast movement.

A frame sequence should only be restarted (see sc_recognition_context_start_new_frame_sequence) if the frame stream is discontinuous, e.g. when the camera is switched off or temporarily stopped.

Single Image Processing Use-Case

Why does scanning a single image not perform as good as scanning with the mobile phone?

There are barcode scanner presets to improve the scan robustness for this scenario. For SDK versions before 7.0, SC_PRESET_ENABLE_SINGLE_FRAME_MODE can be set. For SDK versions 7.1 or later SC_PRESET_HIGH_EFFORT should be set.
A new frame sequence should be started for every new input image by calling sc_recognition_context_start_new_frame_sequence.
The input image should be uncompressed. JPEG encoded image data is often poor as it contains block artifacts.
Try to acquire images that are as sharp as possible and don't contain motion blur.
Disable the code duplicate filter in the session configuration.

Multi-Threading

Dynamic threading is used internally to accelerate the execution if available. The functions of the SDK library are not thread-safe. All context and scanner calls have to happen in the same thread.