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TidBITS#38/FlexiTrace

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FlexiTrace Details

FlexiTrace v1.01
Tree Star, Inc.
116 Memory Lane
Campbell, CA 95008
408/371-8343

Rating:

8 Penguins out of a possible 10

Summary: -- FlexiTrace does one thing quite well, it converts existing graphs and plots into digital data, i.e. it can turn an x-y plot of temperature vs. time into pairs of temperature-time values. Before FlexiTrace can perform its magic, you need to bring an image of the graph or plot into your Mac. This requires that your Mac have access to either a scanner or fax software.

User Evaluation: (on a scale of 0 to 10)

Number of responses: 1 (it's a new program)
Ease of installation: 10
Ease of learning: 7
Ease of use: 8
Power & usefulness: 10
Documentation: 9
Technical support: 8
Overall evaluation: 8

Price and Availability: -- The list price for FlexiTrace is $249. The product is available through MacZone and as a special order item from ComputerWare and EggHead Software. Since FlexiTrace is new, retailers will not be significantly discounting the list price.

Reviewer:

Len Schwer
Staff Scientist
APTEK, Inc.
Internet: micro2.schwer@sri.com

Background Info

I started by purchasing FlexiGraphs, TreeStar's business graphics application, not for generating graphs, but for a crude, yet effective, data digitizing feature. After satisfying my pressing need to convert x-y plots into numbers I could analyze, I thought a letter to TreeStar suggesting certain improvements might be useful. This type of digitizing is something I do occasionally, and any possibility of making it more convenient was worth a small amount of effort on my part.

In my letter to TreeStar, I said I liked the digitizing feature of FlexiGraphs, although I thought the graphics portion of FlexiGraphs was not suitable for engineering applications, and suggested some interface and feature improvements for the digitizing feature. The developers wrote back that they had received several similar suggestions and were in the process of developing FlexiTrace. The original digitizing feature in FlexiGraphs had been a quick hack added because it was easy. Because of my letter, and proximity to a TreeStar office in Los Gatos, I was asked to beta test FlexiTrace. I was also interviewed by MacWEEK for a review of FlexiTrace - see page 22 of the Dec. 18th issue.


What FlexiTrace Does

FlexiTrace is an application for digitizing data. In scientific/engineering work one often needs to digitize line plots, something versus time is typical, that were generated by others, or the original x-y data points are otherwise not available, e.g. "I just deleted that data file yesterday!"

FlexiTrace takes a scanned image (PICT) of the x-y plot, and using a few simple tools, aligns the plot, sets the axes' scales, and digitizes (samples) the data at a user-specified rate. The resulting x-y data points can then be exported via the clipboard or written to an external file for plotting by other applications or for use in spreadsheets.

Thus FlexiTrace eliminates the need for a digitizing tablet and mouse for many digitizing applications. The need for a scanner to capture the image is a slight negative, although the scanner probably has wider application than a digitizing tablet. However, with the increasing number of fax machines attached to Macs, people with onboard fax software can "scan" images into their Macs by sending faxes to their Macs.


How FlexiTrace Works

  1. After launching FlexiTrace use the OPEN... option under the FILE menu to open your scanned image or one of the sample images that accompany FlexiTrace. This opens a FlexiTrace window showing the image to be digitized.

  2. Next you might want to use FlexiTrace's "plumb-bob" tool to vertically align your image (more on this later) and one or more of FlexiTrace's other tools to clean up stray marks (dirt) on the image (more on cleaning images below as well).

  3. When you think the image looks right, use the FlexiTrace "dimensioning" tool to drag a box across the portion of the image to be digitized. This operation is similar to using a Marquee Tool in paint programs.

    The "dimensioning" tool icon is not intuitive to me, but it might be more visible and apparent on a larger screen. The icon shows a two headed arrow spanning two parallel lines, i.e. a typical dimensioning symbol in drafting. My main problems with this icon are its small size and the fact that dimensioning does not necessarily connote selecting the region to be digitized.

    Do not include the x and y axes in the portion of the image to be digitized, or else you will digitize them as well, which is undesirable.

  4. After selecting the portion of the image to be digitized with the "dimensioning" tool, a dialog box appears into which you enter the minimum and maximum values of the ordinate and abscissa (x and y axes).

  5. Before performing the digitization, called "tracing" and hence the name FlexiTrace, you will probably want to change some of the default tracing parameters. There are three logical groupings of these parameters: Tracing, Filtering, and Output. The user can easily switch among these three related sets of parameters using FlexiTrace's unique "Trace Parameter Polylog" window, a kind of multi-function window that uses a horizontal shuttering effect to switch among the three related windows.

    Tracing Options include type of graph (line, area, bar, scatter), sampling method (along ordinate or abscissa), number of samples, and display options for indicating the sampled points on the graph.

    Filtering Options include a "Grid" filter for removing background x-y grid lines that may have been on your original x-y plot and a "Spike" filter for eliminating narrow spikes that are common in experimental data. A third filtering option, "Noise" is also available, though not in the same menu for some reason. The noise filter can be used in multiple passes to eliminate isolated groups of stray pixels; each application of the noise filter looks for groups of pixels with one more additional neighboring pixel, i.e. one neighbor, two neighbors.... (I have also used the noise filter to clean up other scanned images and dirty faxes that arrive via my fax modem; a very handy tool.)

    Output options include mode of exporting/displaying the digitized data (text file, FlexiTrace's "Measurement Window," or the clipboard) and an option for selecting the number of decimal places in the x and y data. All exported data is tab delimited.

  6. Now you simply click on "Trace" and your scanned image is automatically turned into the desired digital data.

  7. If you are not happy with the result you can repeat the above procedure, or parts of it. There are nice (easy) ways of reverting back if you do not like your choices.


FlexiTrace Pros


FlexiTrace Cons

The $249 list price is a bit high. I paid (me, not my company) $149 for FlexiGraphs and did not blink an eye because FlexiGraphs did what I needed to have done, and there was no more cost-effective solution. The same cost-effectiveness is true of FlexiTrace, but I think TreeStar would sell more copies at a lower price; then again, I am an engineer and not an MBA.

Needs a zoom capability. Every time I use FlexiTrace I want to zoom in on a section or expand the view to see more detail.

As mentioned above, the dimensioning tool icon is not intuitive to me, though this may be due to its small size in the tool menu.

Cannot automatically handle multiple lines on one plot. You can use the eraser tool to eliminate all but one line and progress through multiple lines. This seems like a tough problem to solve without a lot of 'smarts' in the software.


Suggested Improvements

I would like to be able to edit the digitized data, i.e. delete, add, or modify points and see where the modified data appears relative to the scanned image. Currently, the user can edit the digitized data in FlexiTrace's Measurement Window, but data edits are not reflected in the in the on-screen representation of the digitized data.

Output of the data in a format other than floating point tab-delimited (a dead give away to the 'business' roots of this product) is desirable. Scientists and engineers usually need data in scientific notation, e.g. 1.00E+03. Something like FORTRAN output formatting would be much appreciated, since the point of digitizing the data is to use it in some other application which quite possibly will not be on the Mac.

Expand the logarithm plotting capability to include natural logarithms. Currently, the user may select a base ten logarithmic scale for the ordinate and/or abscissa. In most scientific and engineering work, natural logarithms, i.e. base e, are typically used rather than base ten logarithms.


FlexiTrace Summary

Overall, what I like best about FlexiTrace is that it does the job just the way I want to have it done, simple yet effective. As a user I have the impression that the developers actually USED this software. Although, I would qualify that intended compliment by stating that some "scientific/engineering" use and features would improve the product for that portion of the market (see my comments below).

As an example of 'usability' features, consider the "plumb-bob" tool. If you have ever scanned in an image you probably know it is almost impossible to align the image vertically and horizontally. This is especially true if you are working from a carelessly made photocopy that is slightly rotated relative to the paper edges. The "plumb-bob" tool in FlexiTrace solves that problem by simply allowing the user to draw a straight line on the scanned image that represents "true" vertical. The FlexiTrace software then rotates the scanned image to make the indicated line vertical, simply and effectively. It makes you wonder why other software that imports or generates scanned images does not have the same tool.

Bottom Line: -- If you need the digitizing features described above, FlexiTrace will meet and exceed your needs. It is a single purpose tool with some useful features that accomplishes the task of transferring graphical data back into numerical form.


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