April 06, 2009
Software Review: Photoshop CS4 Extended For Engineering Imaging
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OK, I’ll admit it up front; I’m a big fan of Photoshop and have been for quite some time. Is it perfect? No. Can its features get complicated to understand and use? Yes. Is it well-suite for “creative types?” Also, yes. Does it also have a place in the technical arena and the engineer’s toolbox? Increasingly, yes. In fact, I find it to be one of the more useful technical/engineering applications, especially coupled with a CAD product, but more about that later.
Instead of trying to cover the myriad features and capabilities of Photoshop CS4, the newest version, we’ll stick to applications of interest to engineers, namely, analysis, measurement, and using a photographic image as the basis for a design using a CAD product. In other words, this evaluation will only entail engineering imaging with Photoshop CS4.
This software review was conducted on a Lenovo ThinkPad W700ds loaner. This is a very interesting machine that actually is well-suited for a graphics product such as Photoshop because it has two beautiful and bright screens (a 17” main screen and a supplemental 10” screen that slides out of the main screen); a digital graphics pad; and hueyPRO monitor color correction. It had an Intel Core 2 Extreme CPU Q9300 running at 2.53 GHz, 4GB RAM, and 64-bit Windows Vista Business. All in all, a hardware platform optimized for this application.
As I said earlier, I’ve used Photoshop for several years, but have experience using it for engineering imaging applications only a little over a year, beginning with Photoshop CS3 Extended. However, I have really grown to appreciate what can be done with it on a more “technical” side, as well as its usefulness on the more “creative” side.
I think some of the most compelling capabilities for engineers are the 2D and 3D measurement tools in Photoshop CS4 Extended. This tool set lets you extract real quantitative information from digital photographic images or drawings.
In Photoshop Extended, you can also measure the dimensions of a photograph or a digital model (2D or 3D) using the measurement feature. You begin by assigning a known measurement to any part of an image or model, then you can take other accurate measurements. For example, you can import a photo of an object, enter a known dimension from the photo, such as the width of a slot, and then generate measurements of any other feature of the object, such as its height, width, depth, distance apart, etc.
Using the measurement feature in Photoshop Extended you can measure any area defined with the Ruler tool or with a selection tool, 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 that keeps track of data including width, height, area, units, scale, and file name. You can customize the Measurement Log columns, as well as sort data within columns, and export data from the log to a text file or spreadsheet.
Setting 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 a time.
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 100-mm machinist’s scale. This absolutely ensured that I had known dimensions. I discovered that the higher the resolution of the photograph, the higher the accuracy of the measurement, as I experimented with photos of different resolutions.
Once the measurement scale is established, 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 tool you’re measuring with. 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. The steps for performing the process are pretty simple:
Setting a measurement scale sets a specified number of pixels in the image equal to a number of scale units, such as inches, millimeters, or microns. 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, although only one scale can be used in a document at a time.
You can place scale markers on an image to display the measurement scale. Scale markers can appear with or without a caption displaying measurement scale units.
Use the Ruler tool to set the measurement scale for a document. You can create measurement scale presets for frequently used measurement scales. Presets are added to the Analysis>Set Measurement Scale submenu. The current measurement scale for a document is checked in the submenu, and appears in the Info panel. Measurement scale markers display the measurement scale used in your document. Set the measurement scale for a document before creating a scale marker.
You can measure using the Photoshop selection tools, Ruler tool, or Count tool. You should choose a measurement tool that matches the type of data you want to record in the Measurement Log.
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 tool you’re measuring with. Area, perimeter, height, and width are available data points for measuring selections. Length and angle are available data points for Ruler tool measurements. You can create and save sets of data points for particular types of measurements to speed your workflow. If your currently selected data points do not correspond to the current measurement tool, you are asked to select data points for that tool.
The Measurement log has columns for each data point you selected in the Measurement Data Points dialog box. Each measurement you make enters a new row of data in the Measurement Log.
If you measure multiple selected areas on an image, one row of data is created in the log containing summary or cumulative data for all selected areas, followed by a row of data for each selection area. Each selection area is listed as a separate Feature in the Label column of the log and assigned a unique number.
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-- Jeff Rowe, MCADCafe.com Contributing Editor.
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