Perform a task on your Personal Computer that could formerly be done only by a large, clunky, expensive machine, and do it better. This Instructable uses a lot of words to describe a fairly easy procedure, but the payoff is worth it. You'll laugh, you'll cry, you'll wag your tail.To see my related Instructables, click on "unclesam" just below the title above or in the INFO box to the right. On the new page that appears, repeatedly click "NEXT" to see all of them.

Step 1: What the Blink?

A Blink Comparator is a device that aids visual inspection of one complex object or image as compared against another. The comparator causes even small and subtle differences between the two to visually blink at the viewer. I provide a source for demonstration image pairs and instructions for capturing and blinking them.
PC running Windows XP, which includes Windows Picture and Fax Viewer. PAINT program to capture, trim and save pairs of images on the computer. The blink effect can probably be implemented using many other programs and on MACs.
To download a free image editor and viewer that will blink two images, see IRFANVIEW in Comments section below this Instructable for details.

Step 2: Grab a Nice Pair

In order to demonstrate the PC Blink Comparator use this link to many pairs of quality images, by Randy Mays, that have intentional small differences, each puzzle is rated for degree of difficulty, and solutions are provided. http://www.washingtonpost.com/secondglance or perform Google search using this phrase enclosed in quote marks: washington post magazine second glance. Try to spot the differences by first looking from one image to its mate. Directions for capturing the images for blinking are provided in Step 4.
The Past Editions pulldown menu allows you to choose more pairs, sorted by publication date. Try the puzzle published Sept07, 08, Brass-Section, for a start. Building-Boom May 25, 08 is rated extreme; also see Dec 23, 07; Aug 19, 07; Sept 02, 07.
This photo puzzle demonstrates the blink principle, but you can use your PC to compare any two items or images, of whatever size, that you can get into your computer by any method. You can quickly find flaws in complex machine parts and stuffed printed circuit boards and detect what might have changed between different frames taken by earthbound surveillance cameras or by satellites.

Step 3: Image Capture, Step-by-step

Image Capture:
To capture the two individual images for blinking, at the Post web site Puzzle for Sept 07, 08, Brass-Section, click Enlarge if available. Right-click anywhere on the photos > copy; Click (-) to minimize Washington Post Magazine window. Click Start> Paint; Click on the white space and use mouse to expand the white space if necessary; Edit>paste. Click the Select tool and carefully outline image #1; Edit>copy; Click (-) to minimize window of Untitled Paint. Start> Paint again to open a new window; expand white space if needed; Edit>paste. Click on the white space and use mouse to shrink white space to match image edges; File>save-as produces dialog box (Save-in: Desktop; type in filename, such as 1brass-section; Save as file type: jpg); Click Save; Click (X) to close window. Maximize Untitled Paint window, repeat steps to capture 2brass-section image and place on desktop; Click (X) to close window. Maximize Untitled Paint window; Click (X) to close that window.

You can use similar steps to capture a copy of the images connected as a pair if you like. The web site allows you to enlarge recent puzzles, but you may not want to enlarge when you capture an attached pair because the result could be too big to fit in your computer screen.

Step 4: Winkin' and Blinkin' Step-by-step

When you have two images you want to compare, set Windows Picture and Fax Viewer as your default viewer. Place only the two images in a folder on your Desktop. Double-click the folder to open it, then choose "View as a slide show" from the available tasks. Repeatedly click any arrow key on the kayboard to toggle between the images, see the differences blink.  Wag your tail.
Windows Picture and Fax Viewer is peculiar to Windows XP. Software included with most digital scanners and cameras can create a slide show that will toggle between two images, as can photo editing programs. To download a free image editor and viewer that will blink two images, see IRFANVIEW in Comments section below this Instructable for details.

Step 5: Background and History

A thorough illustrated history of the past designs and uses of the Blink Comparator, by Steven Escar Smith, may be found by performing a search at Wikipedia.org for Hinman Collator, then click on Reference (1).

IRFANVIEW blinker. Free download from irfanview.com, very capable image and photo editor and viewer, 1.25 Meg, Certified virus free. (Caution: during installation, you will be asked whether to “associate” certain file types, checked from a list, with irfanview. If you check any file types, irfanview will become your default viewer for those types). Once installed, open irfanview: Start>Programs>IrFanView>IrFanView 4.20. Click “slideshow” icon on toolbar of new window, slideshow window will open. Click to select 1) Slide Advancement: Automatic after mouse/keyboard input; 2) Slideshow options: Hide mouse cursor; 3) Play mode: Full Screen; 4) Centered; 5) Show Preview Image. Browse your computer for image pair, select them and add them into slideshow window. Click “Play Sideshow.” Use keyboard arrow keys to toggle between images, which will make their differences blink, and hit Esc key when finished. Click “Slideshow” icon on toolbar of resulting new window to blink another pair of images. U.S.
if you can "see" the pictures in those random dot stereographs, you can do these pretty easily . in the case of the upper and lower pictures, tilt your head 90 degrees, unfocus your eyes, cross them until the elements of the pics that are the same line up. refocus your eyes, and voila! the parts of the image that are different will stick out like a sore thumb. if the images are side by side, don't tilt your head. good idea, though. not everybody appreciates the headaches and eyestrain that go along with my method. :)
i think you can press and hold "page up" or "page down" too if you want to(?) or maybe it's the arrow keys...

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