Auto Crop tool

The Auto Crop tool enables automated cropping of images of flat materials, bound documents or roll film, either on capture or with an existing image.

The tool is highly customizable with options to select a fixed size crop from a Primary variant (master image), and preselect document edges for straightening. The Auto Crop tool is particularly useful when used with Variants, allowing different crops of the same image. The Auto Crop tool is located by default in the Production and QC Tool Tabs in several CH Workspaces, or can be added to a Tab by using the Add Tool option.

Apply Auto Crop to single image

1. Go to the Production or QC Tool Tab, and locate the Auto Crop tool.

2. From the Method drop-down menu select Loose Material for various materials (photos, documents, objects etc.) or Bound Material for bound documents (like a book). This selects the most appropriate algorithm for the subject. Note that the Fixed Size methods are covered later.

3. Click on the Straighten drop-down menu and choose the edge to best align the crop, or select Average based on all four edges or if there’s no straight edge. Choose None to disable the feature.

4. The Pre-Pass option helps the crop tool to better distinguish between the subject and the background if the difference is very small. For example, if a white paper is lying on a white background, you should choose or Low Object-Background Contrast or even Very Low Object-Background Contrast. If the difference between the object and the background is well-defined, None should be selected.

5. With Optimization it is possible to have Levels adjusted automatically after the auto crop, for example, to enhance the legibility of faded text on a paper or to automatically adjust a black and white negative based on the range of tone in the image. This is done by choosing Auto Levels on Interior Crop in the drop-down menu. Note that the adjustment is based on a frame that is 10% smaller than the actual crop to avoid being influenced by a white or black frame. You should also be aware that the way the Levels are automatically adjusted depends on the settings in Preferences > Exposure. Please see the topic Change the Channel Mode here. Select None to disable this feature.

6. Insert a positive or negative - (minus) value for the margin in pixels in the Padding box. Note that a value must be present, so if no padding is required, type 0 (zero).

7. Press Auto Crop at the bottom of the dialog, or select the Crop cursor from top Tool Bar or from the Crop Tool and make the selection. If the On Crop option is selected, the Auto Crop will be applied within the area that is manually cropped. This method can be very useful to help isolate objects that are otherwise difficult to recognize automatically by the Auto Crop feature.

8. If fine-tuning is required, click the Auto Crop button a second or third time as this will attempt to trace the edges with a tighter margin. You can also adjust the crop manually by selecting the Crop cursor (if not already selected) and then click inside the crop area of the image requiring adjustment and drag into place.


Notes:

  • Applying the Undo command in the Main tool bar will cycle through previous steps. Clicking the Reset Crop
    button will revert to the original un-cropped image.
  • The Loose Material setting selects the largest object in the image.
  • The Auto Crop algorithm is designed to recognize rectangular objects and may not work with other shapes; for those objects, you may use a rectangular card or paper as a frame.

Apply Auto Crop to multiple images (Fixed Size)

The workflow is similar to working with one image (see above), however, there are additional steps as the user must specify a master crop as well as the number of images to apply the master crop to.

1. Go to the Production or QC Tool Tab, and locate the Auto Crop tool.

2. From the Method drop-down menu select Loose Material - Fixed Size for same size material, Bound Material - Fixed Size for books and bound documents, or Roll Film – Fixed Size for film.


3. Click on the Straighten drop-down menu and choose the edge to best align the crop, or select Average based on all four edges or if there’s no straight edge. Choose None to disable the feature.


4. The Pre-Pass option helps the crop tool to better distinguish between the subject and the background if the difference is very small. For example, if a white paper is lying on a white background, you should choose or Low Object-Background Contrast or even Very Low Object-Background Contrast. If the difference between the object and the background is well-defined, select None.


5. With Optimization it is possible to have Levels adjusted automatically after the auto crop by choosing Auto Levels on Interior Crop in the drop-down menu. Note that the adjustment is based on a frame that is 10% smaller than the actual crop to avoid being influenced by a white or black frame. Select None to disable this feature.


6. Select the Crop cursor from Cursor Tool bar or from the Crop Tool and make the selection. Note that it is not possible to click on the Auto Crop button when the selected Method is a Fixed Size. To use the Auto Crop functionality, choose the Loose Material or Bound Material method temporarily.

7. Insert a positive or negative - (minus) value for the margin in pixels in the Padding box. Note that a value must be present, so if no padding is required, type 0 (zero).


8. Once the crop is done, click on Set Master Crop.


9. Press the Cmd (Mac) key and select the images to apply the master crop to.

10. Go to the main menu, select the Edit menu and make sure that Edit All Selected Variants is enabled.

11. Press Auto Crop.

12. If fine-tuning is required, press the Auto Crop button a second or third time, or adjust the crop manually by using the Crop cursor.


Notes:
• Straightening is supported by all Auto Crop Methods, within the range of +/-5 degrees.

Tip: Holding the Shift key while applying a crop will override any previous selection.

Film scanning tips:
The new method is a Fixed Size method, much like the two other fixed size methods. Therefore, it requires setting a primary crop on an image before running the auto crop.
The film scanning method requires the primary crop to have the exact size of the film frame to be cropped.
It is important to set a primary crop in an image with the film placed in a “recurrent” position. In other words, if most of the images to be auto cropped have the film horizontally centered in the image, the primary crop should be chosen among those rather than among the few ones with a non-centered film frame.
The method is optimized for the landscape case: the film strip is placed in landscape, with sprocket holes – if any – located at the top and bottom of the image in two horizontal strips.
The film scanning method is optimized for auto cropping of positive images: if the films are negative, the “Film Negative” mode in the Base Characteristics tool should be selected before auto crop- ping. Though some good auto crop results can be achieved anyway.
As usual, good exposure and contrast in the image help the algorithm perform at its best.

Auto Crop confidence feedback for Roll Film

If Roll Film – Fixed Size for film scanning is chosen as the Auto Crop Method, Capture One CH will automatically estimate how successful the auto crop was for each image. This confidence feedback is indicted by three different Color Tags, which is assigned to each variant.

A Green color tag means that there is high probability of a successful auto crop. Yellow indicates a medium confidence that the auto crop was done correctly, while Red denotes a low or very low confidence. Note that the primary image with Set Master Crop will be tagged with a Blue color.

This feature is meant to make it easier and faster to review whether the auto cropping was done correctly. A useful workflow would be to filter the auto cropped variants by color tag. This is done by going to the main menu and select Edit > Select By > Color Tag and then either choosing Red, Yellow or Green.

The images with a high confidence level (Green) can then be reviewed fast with less scrutiny than those with a Red color tag. If fine-tuning is required, press the Auto Crop button again, or adjust the crop manually with the Crop cursor.

Note that the assigned confidence levels are estimates so it is entirely possible that an image with a Red color tag have been auto cropped correctly, while one with the Green tag could be improved upon.

Note: In case of significant frame changes, cropped variants will likely result in medium confidence crops (Yellow tag). The amount of yellow tags can be greatly reduced if a new primary crop is set whenever film size changes significantly.

Apply Auto Crop on capture

Capture One Cultural Heritage can crop automatically on Capture, potentially saving time and reducing unnecessarily repetitive actions.

1. Go to the Production or QC Tool Tab, and locate the Auto Crop tool.

2. Check-mark the On Capture option at the bottom of the dialog.

3. In the Next Capture Adjustments tool, located in the Production tool tab, make sure that the All Other drop-down menu is set to Copy from Last.


4. Capture the first image and follow the procedure for applying Auto Crop on multiple images (see the section above) from step 2 to step 8.

5. Now that the function is setup and enabled, any images captured will have the crop applied automatically after all other settings have been applied.

Tip: The Auto Crop can also be implemented by setting up a keyboard shortcut in the Cultural Heritage version.