JPG or TIFF Scans?
A reader asked me why he can't get TIFFs from North Coast Photo for his film scans. He's somehow been mislead into thinking that TIFFs offer better quality than the JPG versions of the same file.
JPG is a compressed format, even though it can be lossless if saved at the maximum quality level.
There's no difference between the JPG and TIFF versions of the scans I get from NCPS, except that the TIFF versions would fill up quite a few DVDs for each and every roll of film. NCPS doesn't have the time to wait for those DVDs to burn just to satisfy eager newcomers to digital workflow.
NCPS saves their JPGs from the raw data at maximum quality so nothing is lost, except redundant data which is replaced as soon as you open the JPGs.
I'd rather they save the JPGs at a lower quality to save my own disc space, but this way everyone is happy.
NCPS's "Enhanced" scans, higher resolution than offered from any other lab, open as 48 MB images in Photoshop, from typically 10MB JPGs. NCPS's enhanced scans are 17 real megapixels (the same as the LEICA M9 and use no anti-alias filter either), and if you count pixels the way Sigma does, these scans are 48 MP.
I used to scan and save everything as 16x3 bit TIFFs back in the mid 1990s when I knew all the theoretical imaging DSP from my years designing all this at TRW in the 1980s, but after a few years of practical experience working with real photos (as opposed to white-board theory from my PhD colleagues), I realized I was worrying too much.
If a client wants a different file type than JPGs, pros open the JPG file in Photoshop, and SAVE AS whatever sort of file the client demands. If they want more resolution or more bit depth, we simply resize or change the bit depth before we SAVE AS, and everyone is happy.
It turns out that the reason many photo buyers ask for silly things like images at 300 DPI at 24 x 36" as a TIFF for newspaper printing is simply that photo buyers are often less informed about this than pro photographers, none of whom are engineers who really know how this all works. A photo buyer is simply covering his ignorant behind by asking for crazy things like TIFFs.
There's never a problem doing a SAVE AS or RESIZE before shipping the file because the buyer is just trying to check boxes. If you do the right SAVE AS and RESIZE and convert color spaces or whatever and send him what he thinks he asked for, he's happy.
We all laugh when a buyer gets all excited about one format or another, because we all know that his production department has their own copies of Photoshop, and could just as easily open any file format we send. The fact that someone asks for something specifically silly shows us that they don't know how to work Photoshop. (For digital cameras, asking for a raw file is similar to asking for the original film so the buyer can scan it himself; asking for a raw file means that the buyer has his own "look" that he wants to extract from all the images sent from different photographers. The raw file for a scan is the original film; that's why it's called RealRawTM.)
If you want TIFFs, open JPGs in Photoshop, and SAVE AS > TIFF. Quality will be the same, but you'll fill up your discs. This is why no one transmits files as TIFFs, except maybe newcomers and "emerging artists" who haven't yet learned what the working pros did back in the 1990s.
I'm serious. I do this, and so does every pro I know. If buyers were smart enough to figure out that we simply SAVED AS, they wouldn't be asking for stupid things in the first place. Something you learn in order to survive and suceed is not to spend too much time lecturing buyers; just give them what they want. When you get to know them well, then you can try to educate them if it's appropriate.
I once was out in the woods, and a buyer demanded a "high resolution" file. I had no access to my originals, so I dragged it from my website at 600 pixels wide, resized to 6,000 pixels wide, and the buyer was perfectly happy! (This was a particularly ignorant buyer.)
JPGs know what's redundant by using discrete cosine transforms (DCTs) to order the data in a more efficient manner than the original X-Y raster, and then Huffman coding those DCT values in a clever sequence so that redundancies are eliminated from the JPG file with no loss of data (lossless encoding). If you lack the PhD to understand these transforms, you won't understand how this process is lossless.
JPG image data and pixels don't change until you start truncating the DCT values as defined by a quantization matrix. This is the only step in the JPG process where data is thrown away, as opposed to made more compact for efficient, lossless storage. The degree of truncation is set as the QUALITY value when saving a JPG, and depending on your software, the maximum setting is often completely lossless (no truncation of the DCT data and no loss of any image data).
Everyone uses JPGs for scans sent from place to place. Film has so much noise (grain) that it's self-dithering, meaning that at high resolutions, bit depth is almost completely irrelevant. When I realized this, I never bothered saving scans as 16 bit files again!
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