ASK ANDY





How Do I Clean Up Old Photos?



How do I clean up old photos (in a program like Photoshop) and output them as negatives to get new photo prints made?

The key to this is outputting the 'cleaned up old photo' scan on a 'film recorder'. These devices can output negatives or slides/transparencies in 35mm, 5-inchx4-inch, 10-inchx8-inch formats. Photo prints can then be mae from these in the usual way.

The recorder basically works by displaying the image on highly accurate and high resolution cathode ray tube display, which is then photographed. This sounds crude, but the whole device, display and camera are self-contained. You send the image to the film recorder from say, Photoshop, as you would a printer, and the film recorder can do the rest. The film is then removed and the negatives or transparencies are developed, from which you can have photo prints made.

The files are kept RGB to suit the CRT display and are not converted to CMYK as for usual 'printing press' output.

Film recorders come in different resolutions, known as the 'addressable resolution,' referred to as 'K'. This refers to the maximum number of pixels or dots the device can output across the widest dimension of the negative or transparency. Typical recorders are 2K (2,048 pixels), 4K (4,096 pixels), 8K (8,192 pixels) and 16K (16,384 pixels). So a 4K film recorder could output a negative with 4,096 pixels along it's widest edge.

Which to use depends upon the original photo, and the final photo requirements. If the original is 35mm format and you only want to output at 35mm then 2K or 4K would be fine. Any higher and the resolution would be higher than the 35mm could resolve. The problem is the files can be HUGE:

Photo Print Needed Resolution Original Format File Size
5x7 inch 2K 35mm 8MB
7x9 inch 2K 35mm 8MB
8x10 inch 4K 35mm 33MB
20x20 inch 4K 5x4 inch 38MB
3ft x 4ft 4K 5x4 inch 38MB
4ft x 6ft 8K 5x4 inch 154MB
8ft x 12ft 16K 8x10 inch 604MB


The larger files are huge, but remember that's for a 8ft x 12ft PHOTOGRAPH-far higher quality than normal 'halftoned' printing.

Now all I've done is make this sound complicated, next is the 'real world' bit: Say you have a 35mm photo with faults you want to remove, and then get 7x5 inch photos from this. A 35mm negative would be fine for this and could be output from a 2K recorder, the file size being a reasonable 8 MB.

First you would need to get the original 35mm negative or the photo print scanned. If you can, use a negative or transparency for the scan, it'll be high quality, but if these are not available the photo print can be used. The neg or transparency could be sent to a bureau for scanning, you could scan the photo on a flatbed scanner. Which you use, you have to make sure you scan at a resolution to give you enough pixels to match the film recorder output. To scan the 35mm neg to get the 2,048 pixels needed for the 2K recorder you'd have to scan at 1445 dpi. If you used a 5x7-inch photo, you'd have to scan at 2,048 pixels/7-inch=293 dpi.

Once you've got your scan you can clean it up as much as you want, then you'd need to output it. You'd need to send the RGB file to a bureau with film recorder output, they'd take the file, and then send it back to you with the 35mm neg or transparency, from which you can get photo prints developed.

So simply:

*scan original to give the number of pixels needed. 2K=2,048 or 4K=4,096
*clean up scan, send off file at correct size (36x24mm) for output as 35mm neg
*get photo's developed from subsequent neg or transparency
*You can even bend the rules a little, I get 35mm negs done at a bureau at 1200 dpi (gives 1.8K) rather than the proper 1445 dpi (2K) so the files are even smaller.

So the file I send them is 35mm x 24mm at 1200 dpi, 5.52 MB, it's then saved as a JPED (urggg!) which gets the size down to around 550K (!). The next day they send back the file and negative, and I get photo prints developed locally. Even at this lower resolution, you can't tell the photo's have been in and out of a computer! It's rather weird at first, seeing a photograph from an image you know came out of Photoshop!

CONTACT: -Andy.
(Andrew.Davidson@onyx.octacon.co.uk)





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