Wednesday, January 23, 2013

Printing a digital drawing on canvas: how to size for being varnished, stretched, and framed

A new digital drawing is underway. The subject is a recently-rooted cutting of a white African violet that is bursting into its first bloom set against a background of huge silhouetted trees. Here is a mock up with the reference photo of the violet against the background from my digital drawing "Salt Mist:"

This seems like a good excuse to embark on more frequent and more informational blog posts. The topic of this one is how to size a digital drawing to be printed on canvas, varnished, and framed in a metal-section frame.

The first step is to decide the dimensions of the frame and stretchers that will be used. Both stretchers and metal section frames come sized by the inch, so the image must conform to that procrustean constraint. In this example, the final image will go onto 14 x 21 inch stretchers in a 14 x 21 inch frame.

Once the frame/stretcher dimensions have been established, the frame window must be determined. To find these dimensions, subtract the width of the face of the frame x 2 from both the length and the width of the frame. I use Nielsen Style 22 Anodic Black frames with lightweight stretchers. The face of Style 22 is 5/16ths of an inch, so this nominal 14 x 21 inch frame has a window of 13 9/16 by 20 9/16. That gives me a digital file size of 13.5625 x 20.5625.

Inkjet prints on canvas shrink slightly when varnished. Experience has taught me that the shrinkage will be .0625 on the short dimension and .2500 on the long dimension for this size image so the file size must be increased to 13.6250 x 20.8125. To avoid any chance of the white edge of the image showing inside the frame window, I add .25 inch of digital canvas all around the image. I copy the image four times. The first copy I flip horizontally and move so that the left edge lines up with the right edge of the image. Copy #2 gets flipped horizontally and moved so that the right edge of the copy lines up with the left edge of the image. Copies #3 and 4 get flipped vertically. Move copy #3 so that the top edge lines up with the bottom edge of the image and copy #4, so that the bottom edge lines up with the top of the image. I flatten the image and use the clone stamp to fill in the corners. This gives an unobtrusive margin to go under the frame face in case the canvas stretching is not done to mathematical precision. My final file size is thus 14.1250 x 21.3125. I print this on canvas 17 x 24.5," which leaves enough blank canvas to wrap around the wooden stretchers and staple down.

This is how to determine the file size in inches. The resolution (ppi, pixels per inch) is a whole separate question. I have gotten successful prints ranging anywhere from 16 ppi (the "Big Pixel" series) to 360 ppi. I recommend testing your image at various resolutions until you get the look you like best. People who print photographs often recommend resizing images to 300 - 360 ppi for the final print. I find that this blurs the texture of digital drawings and that they print just fine at any resolution that suits the eye.

I hope this information is useful. If you would like to automatically receive more in the future, you are invited to join my mailing list by going to and clicking on the contact button

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