Didger 4
Digitize the curve using the wrapped polyline tool. To use the Wrapped Polyline command:

1. Import and calibrate your well log.

2. Select Digitize | Wrapped Polyline.

3. Enter Minimum Value and Maximum Value with a Wrap Scale of 1.

4. Digitize the upper portion of the log. When you hit the edge of the right bounding box, click F4 on the keyboard to end the first polyline segment.

5. Begin digitizing the next curve. When it returns back to the start of the bounding box, click SHIFT F4 on the keyboard, or double-click to end the polyline.

6. Select Digitize | Wrapped Polyline when you reach the end of the first scale.

7. Click the OK button.

8. Didger will construct the curve and connect the segments into one curve.  

Didger 3
There are a couple ways in Didger 3 to deal with digitizing log curves from a scanned image when the curves go off scale and wrap around.

1. In an image editor, copy the wrapped portion and paste it to its proper position. Load the edited image into Didger and digitize the entire curve at one pass.

2. Calibrate the image using the normal scale (0-100 ohm), digitize the portions of the curve within that scale, export the information. Recalibrate the image using the wrapped scale, digitize the off scale portions only, and export the information. Combine the information from the two exported files into one.

3. Calibrate the image using the normal scale (0-100), digitize the portions of the curve within that scale, go back to Image | Calibrate Image and recalibrate the image using the wrapped scale, and digitize the wrapped portions of the curve within that scale. Didger will automatically put the wrapped portions on the ends of the normal curve in the Plot window. You can then select all the polylines and use Tools | Connect Polylines to make one polyline.