TV and film folks often ask me something like this... "I've finished my project and I need publicity stills. Are stills from my final video printable?"

The the answer is... sure... within certain constraints.

But before I get into the constraints, here are some advisories:

Will screen shots print as well as images created by a good photographer with a good still camera (or even a mediocre still camera)? Probably not. So the images themselves better be compelling.

Will newspapers and magazines be happy you sent them video derived images rather than true stills? Probably not. But again... if images are compelling they will want to show them in their publications.

Okay... so how do you figure out if an image is "printable"?

Though printing guidelines often talk about requiring a certain number of "dots per inch" how many dots per inch a printer really uses is dependent on the line screen of the printer. For a magazine this is typically 133 line per inch – for a newspaper, 85 lines per inch.

(BTW in a computer application, dots per inch means pixels per inch.)

A standard formula says that an image must have double the number of dots per inch as the line screen.

So you're going to be pretty safe if you assume that your image must have 133 X 2 dots per inch. That's 266.

An HD image is 1920 pixels wide.

If you want to figure out how big this image can be printed you take the dots per inch required by the printer and divide it into the width in pixels.

1920 pixels divided by 266 dots per inch = 7.2 inches.

So theoretically... an HD image will print perfectly well 7.2 inches across.

However, there are factors which can mitigate against this:

1. Though the final video image in an HD production is 1920 pixels wide, it may not have started out that way. If it was shot in DV and blown up it is really only 720 pixels wide (the DV standard) so the math is different: 720 pixels divided by 266 dots per inch = 2.7 inches wide.

2. Typically, video is compressed more than images from digital still cameras or film cameras. This compression can cause artifacts and bands of color in the final image. Images must be examined on the screen to make sure they are not unduly degraded by compression. (There can also be problems related to "interlacing" though modern editing systems usually take care of this for you.)

3. Video images are often in motion and so there can be motion blurs. Sometimes this is fine (because it creates an appropriate mood) but generally movement will make video images seem out of focus when printed.

4. If the image has been digitally filtered in the editing process it may have lost resolution in the process. (So.. basic, full color images will work best.)

5. If the image is such that it only makes sense as a still if you crop it, then the REAL resolution is the size of the cropped image. If you crop an HD image to an image 266 pixels wide then you can only print it 1 inch wide. If you crop (or assume the image will be cropped in the final product) you have to do the math to know if it's viable.

6. If the image is "soft" or badly lit or lacks dynamic range... well... if it's not a quality image in HD it won't be a quality image when printed.

In conclusion, if you have true HD images and they don't have the 5 possible problems mentioned above then you can submit them for printing.

But before you do... a piece of advice:

The kind of person who is likely to be able to take your viable HD stills and make them BETTER is a good digital stills photographer. Someone like this will be able to evaluate what you have for problems (the 6 listed above and more) and will know how to optimize the photos for printing. The better they are when you send them to a magazine, the more likely they are to show up in the magazine. A good professional will also know (pretty much for sure) if an individual image will print well or not.

And next time you do a film remember... even a $200 digital still camera is capable of capturing better stills than a $20,000 HD Camera. So make taking stills a part of your production process.

Easy to say. Harder to do. But if you do... your publicist will have better stuff to work with.