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Manufacturing

Photoshop CS3 Extended Measures Up

2 Apr, 2008 By: Jeffrey Rowe

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Latest version from Adobe makes it easy to collect measurement data for analytical engineering tasks.

I've been a hobbyist photographer since I was a teenager, first with film and paper, and eventually all digital -- somewhat analogous to my path as a mechanical designer. With film, I loved processing and printing my shots in the rudimentary darkrooms I had assembled over the years, but the film and processing supplies made it an expensive hobby.

About 15 years ago, I got into digital photography. I was interested in the new technology and I wanted to save some money. As part of that initiation, I purchased my first version of Adobe Photoshop for the PC. It was one of the first releases of Photoshop for the PC, which had previously been available only for Apple's Macintosh platform. Over the years I've become comfortable with a lot of aspects of Photoshop and often wondered if and how some of its features could be applied to mechanical engineering and design.

That question was finally answered when Adobe released a turbocharged version of Photoshop just over a year ago: Photoshop CS3 Extended. This completely new edition of Photoshop is designed to help creative professionals push the limits of digital imaging. On top of everything in the standard Photoshop CS3, it includes a new set of capabilities to integrate 3D and motion graphics, image measurement, and analysis. Adobe claims that Photoshop CS3 Extended can simplify the workflow for professionals in engineering, architecture, medical, and scientific disciplines.

As a mechanical designer, I wanted to try out Photoshop CS3 Extended for inspecting, measuring, and reconstructing a piston rod for an antique engine via 3D modeling. It worked quite well -- in fact, I was so pleased with the results that I can recommend Photoshop CS3 Extended for similar applications. Following is a look at how you can tap this new solution in the mechanical design environment.

2D and 3D Measurement Tools
For engineers, the most compelling capabilities of Photoshop CS3 Extended are its 2D and 3D measurement tools. This new toolset lets you extract real, quantitative information from digital photographic images of any object at any scale.

Using the measurement feature, you can determine the dimensions of an object in a photograph or a 2D or 3D digital model. You begin by assigning a known measurement to any part of an image or model, then you can automatically obtain other accurate measurements. For example, you can import a photo of an object, enter a known dimension from the object in the photo, such as the width of a slot, and the software will generate measurements of other features of the object, such as its height, width, depth, distance apart, and so forth.

Using the Ruler tool or a selection tool, you can measure any defined area, including irregular areas selected with the lasso, quick select, or magic wand tools. You can also compute the height, width, area, and perimeter, or track measurements of one image or multiple images. It's best to choose a measurement tool that matches the kind of data you want to record in the Measurement Log, which keeps track of data including width, height, area, units, scale, and file name. You can customize the Measurement Log using data-formatting and -sorting tools and export data from the log to a text file or spreadsheet.

Creating a measurement scale sets a specified number of pixels in the image equal to a number of scale units, such as inches or millimeters. Once you've created a scale, you can measure areas and receive calculations and log results in the selected scale units. You can create multiple measurement scale presets for frequently used measurement scales, although only one scale can be used in a document at one time.

Experimenting with Measurement Tools
To ensure that I was accurate from the beginning for my first experience with the measurement feature, I set my measurement scale using a digital macro photo of a 6" machinist's scale. This absolutely ensured that I had known dimensions. Experimenting with photos of different resolutions, I discovered that the higher the resolution of the photograph, the higher the accuracy of the measurement.

Once you establish the measurement scale, you can draw lines with the Ruler tool to measure linear distance and angle. Each measurement measures one or more data points. The data points you select determine the information recorded in the Measurement Log. Data points correspond to the type of measurement tool you're using. Area, perimeter, height, and width are available data points for measuring selections. You can create and save sets of data points for particular types of measurements to speed the process.

Following are the steps for performing the process, all very straight-forward:

• Open a photograph or model document.

• Select Analysis / Set Measurement Scale and choose a measurement scale preset for the document, or choose Custom and set a custom measurement scale. Measurements are computed and recorded in the Measurement Log using the scale units in effect when a measurement is recorded. If no measurement scale is defined, the default scale is 1 pixel = 1 pixel.

• In the Select Data Points dialog box, data points are grouped according to the measurement tool that can measure them, and add useful information to the Measurement Log, such as the name of the file being measured, the measurement scale, and the date/time of the measurement. By default all data points are selected. You can select a subset of data points for a particular kind of measurement and save the combination to make it available as a data point preset.

• Choose an image feature and measurement tool to match the selected data points, then either create one or more selections on the image, or choose Analysis / Ruler Tool, or click the Ruler tool in the toolbox, then use the tool to measure the length of an image area.

• Open the Measurement Log palette to examine and export your measurement data to a Microsoft Excel file or database package for documentation or analysis.

Advanced Features
For more advanced analytical engineering, I understand that it is possible for Photoshop CS3 Extended to export to and import data from MATLAB, a technical computing environment and programming language for visualizing data, and visualize the results of MATLAB algorithms. From within Photoshop CS3 Extended, you can view the results of algorithms created in MATLAB, as well as export images created or edited in Photoshop back to MATLAB for detailed analysis.

With some practice, I can see the measurement tools in Photoshop CS3 Extended being used for fairly sophisticated engineering purposes, ranging from inspection to basic reverse engineering. As its engineering-oriented features and capabilities such as the measurement tools continue to evolve, expect to see Photoshop on more engineers' workstations. Its possibilities are wide ranging.