Digital camera files

All digital camera files are adequate to produce good slides. If possible, choose your digital camera's highest resolution. Just send in your files. Crop them for artistic reasons. Work with them in PhotoShop or other programs. Most people send us jpeg, tiff or PhotoShop files. Naturally, better cameras and better lenses produce better slides, but most people are surprised by how good the slides are even when taken with a low-end digital camera.

Resolution

Most people are amazed how good photographic images turn out even if they send us relatively small data files. The images come out smooth, not grainy and the colors are vivid. Of course, larger source images produce sharper slides. But, the files from any digital camera are large enough to produce satisfactory results.

Here are some resolutions for comparison.

• Television 525 X 700
• HDTV (1) 720 X 1280
• HDTV (2) 1080 X 1920

The motion pictures Seabiscuit, SWAT and Open Range are entirely made of 2 megapixel images that have been recorded out to film for distribution. They were all produced using digital intermediates. The advantages of this are better color and a more streamlined editing process. The film was scanned in at a 2 megapixel resolution (1080 X 1920). It was edited as HDTV. Then it was recorded back out to 35mm film for distribution. This process is becoming very popular for high-budget motion pictures. In addition, most computer generated special effects are also 2 megapixel images.

Regular television is only 525 lines or .37 megapixel. Even so, several feature length motion pictures, including Stephen Soderberg's "Full Frontal", many documentaries, and most of the "Blair Witch Project", were shot with camcorders and then a digital film recorder was used to translate them to 35mm for theatrical release. This shows how sharp even a .37 megapixel image can be.

The Phillips plasma high definition television demonstrates how sharp a one-megapixel (720x1280) image can be. The latest Star Wars and Spy Kids episodes demonstrate how sharp a two-megapixel image (1080X1920) can be. Both were shot on two-megapixel digital high definition television cameras and then translated to a film image using a digital film recorder.

What DPI should I use?

It doesn't matter.

DPI stands of "Dots Per Inch", which means the same thing as "Pixels Per Inch". The concept of DPI was intended to accomodate the variable image size intrinsic to printing and publishing.

Unlike printing and publishing, film recorders work with a fixed image size. This eliminates the need for DPI information. So, the film recorder system ignores DPI information. The only thing that matters is the pixel resolution, which is the multiplication product of dpi and image dimension.

The film recorder driver software simply expands whatever image you send so that it will match a fixed device resolution and then sends it to our device. For 35mm slides, our fixed device resolution is 4096 X 2730 pixels. For larger slides and negatives, our fixed device resolution can be as high as 8192 X 6758 pixels. These resolutions were chosen so that the first number is a multiple of two and to obtain the best image from the device regardless of the pixel dimensions of the starting images. It is possible to record at exactly the starting image resolution, but the results would not always be as good.

Should I change the resolution in PhotoShop?

No. Increasing the image resolution will not add more detail. Decreasing the image resolution will reduce sharpness. You may, however, want to increase resolution if you plan on adding text to the image. That way, the text will be sharper.

Should I use antialaised text in PhotoShop?

Yes. Selecting anti-aliased text will effectively double the sharpness of your text.

Adjusting the appearance of an image

Digital photography is more natural than film photography. Your vision system is subjective. Your brain is continually adjusting the appearance of what you see. Digital photography puts this subjectivity into your photographs, thus enabling you to take pictures as you see them. First take the picture, then use your computer to adjustment the image to match what your eyes saw.

Unlike the human eye, film is not subjective. As a result, film doesn't do a very good job of capturing what you see. To put good images on film, studio photographers control the environment to create an image that the film will capture well. Outside the studio, photographers using film have to pick subjects that the film can capture well. A lot of images that look good to the eye simply will not photograph well. So, film photographers face lose a lot of opportunities because their eyes can see something interesting but the film simply cannot reproduce what their eyes see.

Here is the major reason for buying a high-end digital camera. Most high-end digital cameras will save high-definition, raw files. Usually, these raw files are 16-bit-per-channel images that contain 12 bits-per-channel of color data. This gives you 32 times the adjustment latitude of an 8-bit-per channel.

I expect that, within a year, all image adjustment software will support high-definition images. Some cameras, such as the Sigma SD9, come with free high-definition image adjustment software. This software can automatically adjust your image using the powerful brain of your computer. Often, no further adjustment will be needed. If not, the automatic adjustment will often bring you to a good place to start your own adjustments. When you finish adjusting the color, contrast, exposure and so forth, you can save the file in the standard tiff or jpeg format. Then, you can put the tiff or jpeg files on a CD, on the web, use it to make a print or a slide.

You can usually lighten or darken a 12-bit-per-channel file by at least one F-stop. You can also remove color casts. You can extract greater detail at any level. You can extract greater shadow detail, greater quarter tone detail, greater midtone detail, greater three-quarter tone detail an greater highlight detail.

Faithful color reproduction

Digital cameras compensate digitally for color shifts introduced by their light sensors. The user can then digitally compensate for any remaining color shifts using their computer. Finally, the film recorders compensate for color shifts caused by the film itself. This makes very faithful color reproduction possible.

Although they have long used film recorders for computer generated special effects and animation for some time, the motion picture industry is just beginning to shoot major motion pictures on digital cameras. The first two major motion pictures shot this way were the latest Star Wars Episode II and the Spy Kids II.

Spy Kids II director, Robert Rodriguez, was particularly excited about the color fidelity that he was able to get through a fully digital process. The first Spy Kids episode had been shot on conventional 35mm negative film. The second was shot on digital cameras. So, he could really see the difference between the two. When he filmed the first Spy Kids movie, Robert Rodriguez was disappointed when his brightly colored sets came out with dull colors. When he shot Spy Kids II digitally, he was able to capture the vivid colors of his sets for the first time. Digital film recorders were then able to faithfully translate these vivid colors to film.

A lot of professional artists tell me that they are seeing the same thing when they photograph their artwork digitally and then use a film recorder to output the final images. They also like the ability to crop the image digitally.

To be able to produce all of the colors faithfully requires the film recorder to translate the incoming image into the color space of the film being exposed. That way, the red in the film output will match the red that the digital camera captured. This is accomplished by a using a custom color look up table for each film recorder and each film type.

Good lenses

Many of the high-end digital cameras have interchangeable lenses. This gives you the opportunity to pick professional digital photography lenses. These are professional grade lenses designed to provide uniform brightness across the whole image. Cheap lenses are usually brighter in the center, darker in the outside. Even older professional lens designs have this problem. Digital image sensors are more sensitive to this lens problem. So, professional digital lenses have to be designed to produce even more uniform brightness than would be necessary for film lenses.

You should check with the manufacturer to find out which lenses they recommend for professional digital photography. Most manufactures sell lenses that were originally designed for film and may not be ideal for digital photography. Most manufacturers also sell cheap consumer lenses. These are not recommended for digital photography. Sigma, for example, designates their professional lenses as EX and their digital lenses as DG. So, the Sigma lenses most recommended for digital photography would carry both the EX and DG classifications.

35mm aspect ratio

The long dimension of a 35mm slide is 1.5 times the short dimension. Images this shape will fill the entire slide area. Most of our customers prefer to either send in the whole digital camera file or to crop it to their liking. Few people crop their images to fill the whole slide frame.

Comparing resolutions

The important thing in resolution is the number of red-green-blue pixels sets, the pixel-set resolution. High-end digital video cameras have 3 CCDs. This enables them to capture a complete set of red-green-blue pixels for every pixel in the rated resolution. Digital cameras using the Foveon chip, such as the Sigma SD9, also capture a complete set of red-green-blue pixels for every pixel of rated resolution. So the number of red-green-blue pixel sets is equal to the megapixel rating. The megapixel rating and megapixel-set resolution are identical.

Most digital cameras and low-end digital video cameras have a single CCD to record all three color channels. This is accomplished by dividing the CCD into four pixel blocks one of which records red, two of which record green and one of which records blue. So, number of pixel sets is actually one forth of the megapixel rating given these chips. The megapixel rating is four times the megapixel-set resolution. So, you should divide the megapixel rating for these chips by four when comparing to 3 CCD or Foveon-based systems.

This explains why digital video looks so good when it is converted into 35mm motion pictures for commercial release in theaters. The digital video is shot on a 3 CCD camera. So, even though the image is only .37 megapixels, the megapixel-set resolution is also .37 megapixels. It would take a 1.5 megapixel single CCD image to produce the same megapixel-set resolution.