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By Robert Mark

This app is only available on the App Store for iOS devices.


LabStretch2, an iPhone version of LabStretch, is a real-time image enhancement app, designed specifically for rock art researches to use in the field. Images can be acquired from within the app, or loaded from the iPad photo library. They can then be enhanced to see very faint color differences. Unlike the iPad version, LabStretch2 uses 2 screens, Settings and Image. The image thumbnail is also a Run button.

For a description of the method, please see

Usage Notes

1. Images are acquired by Capture Image, which takes a photo from within the app, or Import Image, which selects a photo from the camera roll. If you want to keep the image, use the camera and import the image from the camera roll.

2. Click Run. The image is downsampled and converted to Lab color space. The initial spread is applied. Try OffsetToggle to apply an estimated centering of the histogram before the multiplier (spread) is applied. Select the best toggle and then adjust the sliders. Run after each change. If the enhanced image is almost all one color, work with the offsets.

3. You can use the iPad screen capture to save results.

4. Use Save to capture the full-size enhanced to the camera roll. This requires considerable calculations and, depending upon your CPU speed, can take a minute or more.

For assistance, please contact

iPhone Screenshots

iPhone Screenshot 1
iPhone Screenshot 2
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  • Free
  • Category: Photo & Video
  • Released:
  • Version: 1.0
  • Size: 11.7 MB
  • Language: English
  • Seller:

Compatibility: Requires iOS 9.1 or later. Compatible with iPhone 5s, iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, iPhone SE, iPhone 7, iPhone 7 Plus, iPhone 8, iPhone 8 Plus, iPhone X, iPad Air, iPad Air Wi-Fi + Cellular, iPad mini 2, iPad mini 2 Wi-Fi + Cellular, iPad Air 2, iPad Air 2 Wi-Fi + Cellular, iPad mini 3, iPad mini 3 Wi-Fi + Cellular, iPad mini 4, iPad mini 4 Wi-Fi + Cellular, 12.9-inch iPad Pro, 12.9-inch iPad Pro Wi-Fi + Cellular, 9.7-inch iPad Pro, 9.7-inch iPad Pro Wi-Fi + Cellular, iPad (5th generation), iPad Wi-Fi + Cellular (5th generation), 12.9-inch iPad Pro (2nd generation), 12.9-inch iPad Pro Wi‑Fi + Cellular (2nd generation), 10.5-inch iPad Pro, 10.5-inch iPad Pro Wi‑Fi + Cellular, and iPod touch (6th generation).

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