Preprocessor is function which processes input data before model inference. Every preprocessor has parameters available for configuration. Accuracy Checker supports following set of preprocessors:

• resize - resizing the image to a new width and height.
  • dst_width and dst_height are destination width and height for image resizing respectively. You can also use size instead in case when destination sizes are equal for both dimensions.
  • use_pil parameter specifies usage of Pillow library for resizing. Accuracy Checker uses OpenCV as default image reader.
  • interpolation specifies method that will be used. Possible values depend on image processing library:
    • OpenCV: Nearest, Linear, Cubic, Area, Max, Lanczos4, Bits, Bits32
    • Pillow: None, Nearest, Cubic, Bicubic, Box, Bilinear, Lanczos, Antialias, Hamming
  • aspect_ratio_scale allows save image aspect ratio using one of these ways:
    • width - rescale width.
    • height - rescale height.
    • greater - rescale greater from image sizes.
• normalization - changing the range of pixel intensity values.
  • mean values which will be subtracted from image channels. You can specify one value for all channels or list of comma separated channel-wise values.

  • std specifies values, on which pixels will be divided. You can specify one value for all channels or list of comma separated channel-wise values.

    These parameters support work with precomputed values of frequently used datasets (e.g. cifar10 or imagenet).

• bgr_to_rgb - reversing image channels. Convert image in BGR format to RGB.
• bgr_to_gray - converting image in BGR to grayscale color space.
• flip - image mirroring around specified axis.
  • mode specifies the axis for flipping (vertical or horizontal).
• crop - central cropping for image.
  • dst_width and dst_height are destination width and height for image resizing respectively. You can also use size instead in case when destination sizes are equal.
• crop_rectangle - cropping region of interest using coordinates given as annotation metadata.
• extend_around_rect - scaling region of interest using annotation metadata.
  • augmentation_param is scale factor for augmentation.
• point_aligment - aligning keypoints stored in annotation metadata.
  • draw_points - allows visualize points.
  • normalize - allows to use normalization for keypoints.
  • dst_width and dst_height are destination width and height for keypoints resizing respectively. You can also use size instead in case when destination sizes are equal.
• padding - padding for image.
  • stride - stride for padding.
  • pad_value - value for filling space around original image.
  • dst_width and dst_height are destination width and height for padded image respectively. You can also use size instead in case when destination sizes are equal for both dimensions.
• tiling - image tiling.
  • margin - margin for tiled fragment of image.
  • dst_width and dst_height are destination width and height of tiled fragment respectively. You can also use size instead in case when destination sizes are equal for both dimensions.