Application Settings
Image Preprocessing (Mobile API Scans)
These settings apply only to images sent from the mobile app. Mobile photos require aggressive cleaning to remove shadows and deskewing to fix perspective.
Converts red printer ink to pure white, making only dark pencil/pen marks visible to the OMR engine.
Automatically stretches the image contrast to cover the full dynamic range before thresholding.
Darkens mid-tones. Default 1.3.
Converts the image to strictly 1-bit Black and White. Any pixel below a brightness of 200 becomes Pure Black, and 200+ becomes Pure White.
Attempts to fix skewed mobile scans.
Image Preprocessing (Web App / Flatbed Scans)
These settings apply when you upload batches via this Web Dashboard. Scans from physical scanners are usually already flat and evenly lit, so we recommend leaving these OFF to preserve faint pencil marks.
Converts red printer ink to pure white, making only dark pencil/pen marks visible to the OMR engine.
Automatically finds the darkest and lightest pixels in the specific image, stretching them to pure black (0) and pure white (255) respectively. This fixes washed-out grey scans, making pencil marks distinct without completely destroying faint shades like Binarization does.
Adjusts the brightness of mid-tones. A value > 1.0 darkens light pencil marks (e.g. 1.3), while < 1.0 lightens them. Default: 1.0 (No adjustment).
Converts the image to strictly 1-bit Black and White. Any pixel below a brightness of 200 becomes Pure Black, and 200+ becomes Pure White. This removes all grayscale background noise, but will override the more nuanced 'OMR Threshold' below. Otsu has been removed from this pipeline.
Leave OFF for perfect flatbed scans. Turn ON if your scanner feeds paper crookedly.
OMR Settings
The brightness cutoff line. 0 = Pure Black, 255 = Pure White. Lower values ignore faint marks and noise. Recommended: 110-130 for typical pencil marks.
Required percentage of dark pixels to count a bubble as filled. Higher values reduce false positives. Recommended: 20-25% for pencil marks, 40%+ for dark ink.
Default bubble sampling size in pixels. Smaller windows better detect thin marks. Recommended: 20px for typical bubble sheets.
Default shape for bubbles in new templates.
Default corner type used by the OpenCV detection algorithm.
Corner type used by the legacy corner detection algorithm.
Metadata OCR Settings
Select the default engine used to extract text from drawn metadata areas (like Name or ID) when starting a new session or regrading.