Archived posting to the Leica Users Group, 1999/10/12
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Actually, scanning film in the consumer-level slide/negative scanners that many people on the LUG use such as the Nikon Coolscan/Polaroid models/etc. are quite a different proposition entirely. Rather than trying to have a CCD array in the film plane which captures an entire scene in one exposure, a desktop scanner utilizes a smaller, linear CCD of higher resolution which is dragged across the film plane capturing many smaller exposures sequentially that are combined to form the entire image. The bottom line is that instead of going to the trouble of having a 2 million pixel CCD to get a certain level of image quality, you can have a much smaller one, thus getting more with less. One additional thing to consider here is that while a digital camera can consider itself a "2 megapixel" camera as many do these days, it is important to keep in mind that this is the device's CCD pixel density, not the actual number of pixels in the final image file that it generates. This is due to the fact that three imaging sensing pixels in a CCD are needed to determine the color of a single pixel in the final image. The bottom line is that there is only 1/3 the effective resolution in a CCD that its stated resolution would suggest. The rest of the data is interpolated to give you an image file of the stated resolution (i.e. 1800x1600). The bottom line is that, as a recent article pointed out (I wish I could remember where I read this), that you would need a digital camera with a CCD pixel resolution of three times its stated value to equal the resolution of a given negative/slide scanner image. So in order to have a digital camera that matches the true resolution of a given slide scanner with a hypothetical final image resolution of 2.1 megapixels or 1800x1600, it would actually have to have a CCD of 6.3 megapixels. > ------------------------------ > > Date: Tue, 12 Oct 1999 18:57:13 +0200 > From: "Anthony Atkielski" <anthony@atkielski.com> > Subject: Re: [Leica] paperless??? > > Well, scanning film involves all of the same operations and requirements you > just cited above as problems with digital photography. Why are these obstacles > when the initial capture of the image is on a CCD, but not obstacles when the > initial capture is on film which is then scanned? The size of the files is the > same--if anything, the film scans produce even larger files. >