How to photo-print (or print) a properly-sized reference scale

Back to reference scale page

Thumbnail of image file, with three scales

The goal is to make a photo-print (or print) with the scale being exactly 10 cm long.

Printing to a standard desktop printer (rather than sending the file to a photofinisher) is straight-forward: Print a 'standard size' image file obtained below. Printed 'actual size', it should appear with the scale 10 cm long. The standard size image has a DPI setting of 200 dots/cm = 508 dots/inch.

Photo-printing using a photofinisher yields a better grey square. This would be easy too if photofinishers printed our images sized perfectly to a 4x6 print, but they don't; it's too difficult to align images exactly with the print boundary. So instead they project the image upon an area slightly larger than the print. That means we cannot predict the result and need to check the length of the scale as it appears on the received photo print.

When the photo print is received, use a ruler to measure the 10cm scale on the print as accurately as possible (you should be able to estimate fractions of a millimeter and thus get centimeters to two decimal places, eg., 10.13 cm). If the printed scale is as close as you'd like to 10 cm, you're done! Just use scissors to cut out the scales. Otherwise, you can adjust the image size and reprint it, using the custom image generator below.

Reference scale generator/downloader

Use the buttons below to generate and download a reference scale image file to save on your computer/device. Print the image file, or (better) send it to a photofinisher for printing as a 4x6 inch print. Matte finish reduces glare and fingerprints.

Standard size

Choose this if you haven't already tried printing a scale.

Custom size

Choose this if you printed a scale and it was not exactly 10 cm.

Photofinisher printing machines are usually stable, so when you get one well-sized, it will probably reprint at that photofinisher without need for further adjustment (assuming all machines at that service are set up similarly).

The red 'arrows' are cropping indicators; they provide information, just for interest, about how much of the image was cropped by the photofinisher. Their scale is in pixels.

Use scissors to cut the reference scales from the print along the guide lines and at the base of the millimeter scale.

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Copy of generated reference scale image file