Clip Frames (Activity)
|
This article is about the current version of Grooper. Note that some content may still need to be updated. | |
| 2025 | 2.80 |
view_module Clip Frames is a specialized Activity for processing microfiche in Grooper. It extracts defined areas from microfiche card images, creating new image frames or layers for focused analysis or processing.
The Clip Frames activity is a key step in Grooper’s microfiche processing workflow. Its primary function is to crop and extract individual document frames from each strip of a microfiche card, producing separate page images for downstream processing such as OCR, classification, and data extraction.
- Grooper's microfiche processing components were developed for and tested using Mekel brand scanners. Please contact support (support@bisok.com) to verify compatibility with other microfiche scanners.
What is Clip Frames?
Clip Frames is a specialized activity that takes the frame location data generated by the Detect Frames activity and uses it to extract each detected frame as a separate image. Each frame typically represents a single page or document stored on the microfiche card.
What is it for?
The main purposes of the Clip Frames activity are:
- Frame extraction: Crops out each detected frame from the assembled strip images, creating a new Batch Page for each frame.
- Image preparation: Applies optional rotation correction, padding, and compression to ensure each extracted page is clean and ready for further processing.
- Error flagging: Flags the Batch Folder if any expected frames are missing after extraction, alerting users to potential issues.
How does it work?
The Clip Frames activity performs several key operations:
- Frame image extraction:
- Loads the frame location data (typically from "FicheStripData.json") produced by the Detect Frames activity.
- Iterates through each tile image in the strip, determining which frames are fully or partially contained within each tile.
- For frames fully contained within a tile, crops the frame directly from that tile.
- For frames that span two tiles, combines the relevant regions from both tiles to create a seamless frame image.
- Image adjustments:
- Applies the "Tile Rotation" property to correct for any rotation in the original tiles.
- Adds padding around each frame using the "Padding" property, if specified.
- Saves each extracted frame using the specified "Compression" settings, or defaults to the root node’s settings if not specified.
- Page creation and organization:
- Creates a new Batch Page for each extracted frame, naming and indexing the pages according to the card and frame number.
- Organizes the pages within a "Frames" subfolder of the current Batch Folder.
- Error handling and flagging:
- If the number of extracted frames does not match the expected count, flags the Batch Folder with a warning message.
How is it used?
The Clip Frames activity is typically used as the third step in a microfiche Batch Process, following Initialize Card and Detect Frames. To use it:
- Add the Clip Frames activity to your Batch Process after Detect Frames.
- Configure the following key properties as needed:
- "Layout": Specifies the fiche card layout, ensuring correct frame indexing and organization.
- "Tile Rotation": Corrects for any rotation in the scanned tiles.
- "Compression": Sets the image compression for saved frames.
- "Padding": Adds extra space around each frame, if desired.
Example workflow
After Clip Frames completes, each frame is available as a separate Batch Page, ready for further processing such as image cleanup, OCR, or data extraction.
A typical microfiche processing workflow might look like this:
- Fiche scan files are imported into Grooper.
- Initialize Card – Organize tiles and create a preview image.
- Detect Frames – Detect frame locations on each strip.
- Clip Frames – Extract each frame as a separate page.
- Additional steps such as image cleanup, OCR, classification, and data extraction.
Best practices
- Always run Clip Frames after Detect Frames to ensure accurate frame extraction.
- Review flagged Batch Folders for missing frames to catch scanning or detection issues early.
- Adjust "Tile Rotation" and "Padding" to optimize the quality of extracted page images.
- Use the "Compression" property to balance image quality and file size for downstream processing.