Gamma Tech Process

Copyright

We are committed to protecting copyrights. Each customer is required by US law to own the right, or obtain permission, to use any image before the image is uploaded for imaging at Gamma Tech.

Forget PPI - it doesn't matter

72ppi or 1200ppi are all the same for film recording, it doesn't matter. What makes a difference is the number of pixels in the image. We recommend at least 1200 x 1800 pixels.

For most purposes, such as art show submission, if the image looks good on your monitor when viewed at 100% it will be fine for a 35mm slide. For publication or portfolio a larger image would be suggested.

Image Size

Resampling an image

This option will either remove data from the image to make it have less pixels, or insert data into the image to make it have more pixels. In either case the quality of the image is changed by resampling. If your image is 1000 pixels wide and you resample it to 500 pixels, 1 of every 2 pixels in each dimension will be deleted to make the new image. If you resample from 1000 up to 2000 pixels the software will add intermediate lines in each dimension based on the original image, and give you a new image 2000 pixels wide. In either case, the quality will be affected by resampling, which is why I don't recommend resampling your images before sending them to us.

Resizing an image

This option will only change a bit of code in the file, which will be read by some output device (such as a printer) to determine how many pixels to use for each inch printed. If you have an image that is 1000 pixels wide, and the file resolution is set at 100 pixels per inch, a print from the file will be (1000 pixels/100 pixels per inch) = 10 inches. If you change the resolution to 500 pixels per inch, the resulting print will be (1000 pixels/500 pixels per inch) = 2 inches. In both cases the image is unchanged, only the data in the file header has been altered.

All film recorders are based on fixed sizes (35mm, 120, 4x5 etc). Resolution in the file header is not used and the image is interpolated by hardware to the appropriate size for the film being recorded. Some companies use this as an advertising point, saying that your files are exposed at exactly 1:1 with no resampling, giving you the sharpest image possible. The fact is that any company using film recorders is doing exactly the same thing, that's just the way it works, and the hardware interpolation is much better than a resampled image because the film recorder hardware is customized to produce the optimal result with that particular film recorder.

For good quality 35mm slides I recommend files 1800x1200 pixels or larger. Smaller files can be acceptable if there is not much fine detail in the image. Smaller pixel size images will appear less sharp on film.

A chart of recorder resolutions is given below. Full frame 35mm slides are 4096x2732 pixels, also called 4K. I can image at higher (or lower) resolutions, but 4K is optimal for 35mm film.

Rotation, Borders and Crop

By default your image will be rotated if necessary to produce the largest image on the film and scaled so that nothing is cut off by the mount. If the image does not fill the frame, the extra space outside your image will be black by default. If you want the image to fill the live area you will need to crop the image to to a 2:3 aspect ratio (4x6, 6x9, 8x12 are all a 2:3 ratio).

Images that are not in 2:3 aspect ratio are scaled to fit the 35mm frame with no cropping. The space outside the image will be black by default. If you need some color other than black you will need to add it to fill the 2:3 ratio.

The image being recorded in the film recorder is horizontal (Landscape). Vertical (Portrait) images are rotated 90 degrees to give the largest possible image on the film. If you want a vertical image centered in the horizontal frame with black on the sides you will need to let us know when you place the order, or increase the canvas size to the 2:3 ratio.

Here's a reference chart to help visualize the options:

What you need	Your file	The film	Mounted slide
Full frame horizontal slide
Full frame vertical slide
No crop from less than full frame image
Vertical image
Vertical image on horizontal slide

Crop

I record the film so that the image is not cut off in the mount. The aperture of the plastic mount is (approximately) 3840x2560 pixels, and does vary slightly depending on the lot number of the mounts. If you submit images that are the full 4096x2732 they will be recorded at that size, and if they are mounted some of the image will be cut off by the mount.

Slide Mounts

Slides are mounted in plain white mounts with no writing or imprinting unless you specify the film to be unmounted. Unmounted film will be shipped in archival sleeving.

Color Profile

You can work in any profile, but when you send files for slides they should be in either Adobe 1998 or sRGB color. I balance the film recorders to a neutral color and a brightness curve that will match very closely to a calibrated display with the image in either Adobe 1998 or sRGB. (see "Viewing Slides" below) Images submitted in the wrong profile will not image correctly.

Color Space

We get asked quite often if we can provide a profile for the camera. The short answer is that it's not necessary, here's why. Each device, monitor, printer, film etc. is capable of producing only a part of the colors the human eye can perceive. This is called the color gamut of the device. The color gamut of a printer covers less color space than most monitors, so profiles are calculated to eliminate, limit or adjust the colors displayed on the monitor so they will closely match the color gamut of the output device and what you see will match what is printed. Film has the capability to produce every color you see on the monitor, and therefore no color profile is needed. This concept is illustrated by the chromaticity diagram shown here.

Because film has this capacity it is best to use the color space which reproduces the most colors on your monitor. Adobe RGB or sRGB would be my recommendation. Very few displays are capable of displaying more than the sRGB color space, so if your display is calibrated, and you can see the steps in the gray bar above, the slides you get back will look just like your screen when viewed correctly.

Color Balance

I have written custom software to balance my film recorders to the absolute highest quality standard available, and I monitor both film emulsion and processing extensively. It took nearly 15 years to refine this process, which allows me to guarantee the most accurate color available.

Because film can produce a much wider range of colors than a display monitor, comparing the slide to a display is difficult.

If you don't have a calibration system here's a very simple way to judge your monitor color, density and contrast without spending money on software and calibration devices. The scale below is a 16-step gray scale. First of all, it should look gray. You should also be able to see differences in the steps indicated. Steps 15 and 16 are difficult to see on any monitor, but you should at least see a difference from 14 to 15, and some LCD monitors may have trouble with the brighter steps. If this scale looks good on your monitor, and your files look good on your monitor, then you will be very pleased with the slides.

File Formats

I recommend sending files in JPEG format saved with high quality settings.
At the same pixel size there is no visible difference between slides made from a JPEG or a tiff file, but the JPEG file will upload much quicker. Although I recommend JPEG, I can image film form TIFF, PSD, BMP, TGA, PDF, PowerPoint etc.

For more detailed information on specific file formats please refer to our Format page.

Your files need to be in 8-bit RGB or Grayscale. (If you don't know what this means, then you probably don't need to worry about it.)

Files I recieve are converted to RLE compressed TGA files for recording. During the conversion borders are added if necessary to avoid cropping in the slide mount, and rotated if necessary. Camera hardware takes care of scaling requirements to fit the image to the film.

You may specify any special instructions for borders, crop or format on the order form when you submit your order. I don't use postscript rip software for presentation programs because there are always potential problems with rip software. Instead I rasterize files to the physical resolution of the camera so they maintain the highest possible quality.

Whatever format you send, these are some rules for the best result:

Film Recording Mechanics

The film recorders I use are some of the best ever manufactured. The diagram to the right demonstrates the basic concept of how a film recorder works.

A film recorder consists of an extremely high resolution monochrome CRT, cut-off filters, shutter and a lens/camera option.

The file is sent to the recorder one channel at a time: Red, Green, then Blue. If you were to look at the Film Recorder CRT during an exposure, you would see a bright spot of light scanning each line of the image, working it's way from top to bottom.

The exposure takes from 30 to 90 seconds for 35mm, and can be up to 25 minutes for a full resolution 16k 4x5 or 8x10 exposure.

For each channel a corresponding cut-off filter rotates into the light path. This results in Red, Green and Blue exposures on the same piece of film to form a complete image.

When all 3 colors have been exposed the image is complete and the film can be advanced.

All 35mm digital slides are imaged at 4k resolution (meaning 4,096 pixels in the long dimension) using Agfa Alto 16k film recorders.

My calibration methods for this process are unmatched. If you send a grayscale image you will get back a slide with no color bias - GURANTEED!

Agfa Alto with 35mm bulk option.	Agfa Altos with 35mm bulk and 8x10 film options.

Film Processing

Even the best film recording is garbage without great film processing. In the past 30 years I've operated several E6 labs, and Gamma Tech has run film at 6 different labs in the past 25 years. Film is now processed by (in my opinion) the best E6 lab in the country.

Processing is done at Denver Digital Imaging in Denver Colorado. At right is a photo of their Refrema E6 150 GL-Custom film processor, which provides accurate and consistent processing from 35mm to 8x10 sheet film.

Mounting, sleeving, final inspection, packaging and shipping of orders is done at Denver Digital by a team of highly qualified technicians.

Digital slides are shipped within 2 working days in plastic mounts and sleeved in archival plastic pages. (Sorry - Cardboard mounts are not available.)

I stand behind our work 100%. If you are not happy for any reason with the quality of the recorded image I will either reshoot the film at no charge or I will refund the full amount of your order.

Viewing Slides

People have complained that color didn't match when they held the digital slide up to the window, or a wall. This is often the weak link in the chain. When you look at the slides and compare them to your display you should make sure you are using a color correct light source. Viewing conditions are detailed in ANSI Standard PH2.30-1989. The basics of this standard are:

If you don't have a viewer that meets these standards you may feel that the color does not match, and there won't be much we can do about it. Suitable illuminators are available from just about any supplier of photographic products.

Correcting for Bad Viewing Conditions

My film recorders are maintained at a constant calibration for color and density. When viewed on a color correct light source the slides should match your calibrated display, however there are instances when this does not correspond to the real world. The result is that you get slides that don't exactly match when projected. There are ways to correct this condition. The most common method is described here.

This technique requires that you can directly compare the projected image to the display you're trying to match.

The desired result: The transparency matches your monitor when viewed with an ANSI standard viewing device.

The problem: The projector in this case is the wrong color temperature does not match the monitor and the projected image appears red.

The fix part 1: First adjust the image (not your monitor) using an image editing program such as PhotoShop, Iedit, Corel Draw or whatever you use. Note which tools you use to adjust the image, and how much correction you add to the file. In this case let's say we add 10 units of red to match the monitor to the projection.

The fix part 2: Starting with no correction make the opposite adjustment to the file that you made in part 1.

In this case, since 10 units of red matched the off color projection, subtract 10 units of red and save a copy of the image.

The new file, with the opposite correction, is sent for a slide which will be off color (-10 units red) but when projected will match the display, because the projector will compensate back to the desired color.