.

I created this image about one year ago on color transparency film (Fuji Provia F), medium format 6x6, using the venerable Bronica SQA. (That was the last time I used film.) Scanned to digital at 4000dpi, the digital image is a bit more than 70 megapixels, allowing a life-size 36-inch print. At 33x33 inches, this image was printed on a canvas gallery-wrap, stretched on a wood frame much like a painters canvas. The image wraps around the edges, 1.5 inches on every side, such that the face of the print is 30x30. This is the second canvas gallery-wrap I have printed this year. The first was a panorama, five feet wide.

What I want to share with you is a comparison of three different print types.

Printing on canvas has become very accessible these days, available from many vendors. Upload the digital image to the vendors website, choose your options, and provide payment. I chose Artistic Photo Canvas, having seen the excellent prints first hand. Of course, canvas is remarkable for the texture. APC uses only a high-quality cotton canvas and provides a protective clear coat over the final print. However, be aware that the maximum black density (Dmax) and the highlight intensity cannot match printing on more traditional photo papers. The overall contrast is therefore reduced. Although APC boasts one of the highest Dmax available on canvas, it is poor compared to traditional photo paper. None-the-less, it is an impressive way to display a photograph.

Then, I had the same image printed on metallic photo paper. This print is craaazy! The highlights in the image have a 3-dimensional quality that seems to exceed the 2-dimensional nature of the medium. Compared to a traditional photo paper, metalic paper may exhibit some minor loss in subtle color gradation; but holy cats, man, it is stunning. It is not suitable for every image; for example, I would not recommend metallic paper for portraits. To get the most from a metallic print, ensure good illumination; without good light, it tends to look like any ordinary print.
.

Pixels (part 1)

Perhaps the most common question regarding digital photography is ... how many megapixels do I need? The answer depends upon how you intend to use the photo. You need to answer two questions: how large will the photo appear (inches or centimeters) and how many dots per inch (or centimeter).

If you want to share it on a computer screen, one megapixel is more than enough. Why? Computer displays typically have either 72 pixels per inch or 96 dots per inch. So, for example, to display a photo at a size of 6 by 9 inches, you need (6 x 96) x (9 x 96) = 497,664 pixels = 0.497 megapixels.

Computer screen: 72 - 96 dots (pixels) per inch
Photo print: 240 - 300 dots per inch
Magazine: 100 - 200 dots per inch
Poster or banner: 100 - 150 dots per inch
Billboard: 10 - 20 dots per inch

Magazines print fewer dots per inch. If you look real close, you may see the individual dots, but maybe not. It depends upon the exact printing equipment and the tendency of ink dots to blend together. Billboards, viewed from far way, use very low resolution simply because it is not apparent from far away.

So, here is another example. For a photo print 6 x 9 inches, you need (6 x 240) x (9 x 240) = 3,110,400 pixels = 3 megapixels. More pixels in your camera means that you can get larger prints without sacrificing quality. Using the same math, you can easily see that a 20 x 24 inch print needs 27 megapixels.

You may ask: 240 dots per inch? My printer supports 1000 dots per inch.
OK, here is the bottom line. If you print at the higher resolution, can you see a difference in the final print? You might see a tiny difference, but 240 dpi usually provides excellent quality and sharpness. If you are using a photo lab to make your prints, consult their guidelines, but 240dpi or 250 dpi is very common.