Forensic Actions
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For newer versions of Photoshop, please go to:
https://ori.hhs.gov/advanced-forensic-actions
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FORENSIC ACTIONS for Photoshop
An "Actions set" is a routine that runs within Photoshop® that can be used to automate image analysis sequence or to create new Droplets. An Action set can be easily customized, it is a considerable smaller file (2-30 kB) than its Droplet, and as a nonexecutable file it can be easily sent as an email attachment.
The separate Action files must be loaded, saved to, and used within the application, but they can be easily tailored with toggled settings for their individual steps. For example, image processing can be stopped at any point in the sequence in one Action set, and then restarted at another point in a separate action set.
USE: Download and (when queried) Save (copy) the Action Set to any location in the Photoshop Folder. Then, in Photoshop, load the Actions through the Actions Palette for use.
At that point the Action can be modified as wished. For any image you can select the steps of the Action set you want to use, stopping/starting at any stage in the sequence, moving between actions, etc, activate or de-activate the dialogue to add flexibility or, conversely speed the throughput. For example, one can run an Action, then manually use the slider in the History Palette to return a processed image to an intermediate step in the sequence, then activate a sequence from the middle of a different Action set in the Action Palette. Actions can also be used to batch process images in pre-publications screening.
For use with a browser, one needs first to drag the icon of the image of interest into the Photoshop application window, select the Action from the list, and then run it, etc. (However, one can start with an Action set to customize your own Droplet for a fast-acting interface to the browser.)
Actions are fully cross-platform; but they are not downward compatible. These versions appear to work in all version of Photoshop® v. CS2 and higher.
Select and Save the Action Set to any location in the Photoshop Folder. Then, in Photoshop, load the Actions through the Actions Palette for use:
| Title | Description | Format | Download |
|---|---|---|---|
| Download Full Set | Download all Forensic Actions listed below in a single zip file. | .zip |  |
| Features in Dark or Light Areas: | This Action simply applies Histogram Equalization, which may reveal areas of erasure in dark areas, or areas of whitening in bright areas. The process is most effective if the contrasting borders can be first cropped from the image, and restricting the "set-up" area to an area where the range of intensities is reduced. Then selecting "equalize entire image based on selected area" option will force an overexpansion of the new histogram to create a too highly contrasted image, but one that may reveal small boundaries where splicing occurs. Inconsistencies revealed by this process should be explored in more detail with the "Forensic Gradient Map." | .atn (zipped) |
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| Forensic Gradient Map: | This Action combines several features of the two early droplets ("Colorise Shapes & Details" and "Solarize Margins & Edges.") Forensic details in the background on in fine structure surrounding the features in question may be used to visualize evidence to assess whether two features are the same. This droplet uses a non-linear contrast adjust and amplify differences False coloring facilitates detection of small differences in gray shades that would be otherwise imperceptible. The principles are demonstrated in an attached PowerPoint slide. | .atn (zipped) |
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| Useful Gradients A: | These are a series of Look Up Tables that were created for the Forensic Gradient Map: A Look Up Table (LUT) that has multiple cycles for contrast or color are best suited for an area in images that has shallow contrast and/or low detail. Details in images with which contrast or steep spatial gradients (small features) will be better revealed using LUT’s with fewer cycles in contrast or color. See the "Comments: in the READ ME file #1 for further advice about their use. | .atn (zipped) |
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ACTIONS FOR COMPARING TWO IMAGES:
Color Coded Overlay: Any Action in this category overlays two images, and color codes each so that individual features in the overlap can be linked back to their respective image.
To use, make sure the images are open within the Photoshop application, and then simply select the run button (Green wedge) in the Action’s Palette. onto the icon of the Droplet, and the sequence will proceed.
The specific color scheme may vary, but in general regions where dark features overlap will appear RED, and areas of overlapping background will appear CYAN. Features unique to one or the other image will be WHITE or BLACK. If the same object is common to both images it 1) must be RED and 2) must have a uniform boundary of either BLACK or WHITE. The image can be resized and reoriented using "Free Transform" in the Edit Menu to test alignment of the images. The method of comparison is completely analogous to the widely used colocalization technique that is a widely used and accepted method in cell biology.
The color-coding for features in the overlapped image that are not common to both sources may vary depending on the type of image. In this case, a useful technique for identifying the source of any features is to pre-label each respective image with a large letter or number in the same relative location, such as the upper left corner. The color of the non-overlapping portion of the respective labels will then serve to identify the origin of any specific feature in question.
Actions for Specific Types of Image Overlay are as follows:
Comments are Welcome:
Simply email ORI using "Forensic Actions" in the subject line.
Set of Advanced Forensic Actions: Additional Forensic Actions that are compatible with Photoshop v CS4-5, advanced look-up tables for improved visualizations over a wide dynamic range, with instructions for use and additional Look UP Tables are also available.