[GH85Carrera]

The one gig files start life that way. We shoot aerial negatives and the film is 9 inches wide. Each frame of film is 9x9 inches. We scan them at 12 micron or 2,116 PPI with a photogrammetric scanner. The reason they are so big is we cover a lot of area at high resolution. I am working on a photo of clients property right now. They own about one square mile of property and are developing the area. They will want a print of each 1/4 section of the property at a scale of one inch = one hundred feet. They might want just a 40 acrea area at 1'=50'. To make that a sharp & detailed image the overall area and each 1/4 section the raw scan is 19702 pixels x 19702 pixels overall.

The final image of the entire square mile will have a pixel resolution of over 1/2 foot per pixel. The easy to understand explanation is that if the customer wanted a print that was one square mile in size (OK no one wants a print 5,280 x 5,280 feet across) each pixel of the image would cover 6 inches. When the print is made at logical sizes like 3 feet x 3 feet the detail is very high, and we can print 1/16th mile of area and still have high detail.

All we do with Photoshop is tweak the color of the image from the scanner & remove the occasional dust spot. We scan the film very flat or low contrast to get all the detail in shadows and highlights. It is easy to add contrast. If the image starts contrasty and the shadows are just solid black and the highlights blown out there is no way to fix that.