.bmp vs .tiff or .jpg

Discussion in 'Digital Darkroom' started by diegobuono, Jul 25, 2006.

  1. Some weeks ago I went to the usual pro lab and asked a print (30 x 30 cm ) from
    a slide. The print came out pretty good but with some spot/dust on it.
    Yesterday I was again at that lab and by talking with the guy that do the scan
    for me I asked to check if the file of the scan of that slide was already
    available. He was not sure it was available because I asked a direct print and
    was not made by him. With his surprise the file was there in the server so he
    saved a copy for me.
    Now come to the point:
    1) when a direct print is asked the slide is scanned right? Is this process
    different (different machine?) from a pro (imacon o drum) scan?
    2) the file was a .bmp, ( 3.035 X 3.035 pixel at bit per channel)is there a
    reason why it is saved as .bmp? It is an automatic choose of the machine?
    3) I want to use te file to clean the image from spot/dust, it is suitable for
    this purpose or the .bmp file has some weak point compared to .tiff.
    4) Do you recommend to save it as a .tiff or leave it in .bmp?
    Thank you in advance for your help.
  2. Hi Diego, All I can really comment on is your last question: .bmp files are huge and don't offer much flexibility. On the other hand .tiff files are quite a bit smaller and (some) can even support layers in programs like Photoshop. Personally, I'd never save a photograph as a .bmp file - they take up a lot of space.
  3. Thanks Beau for your advice, if now I save the image as a .tiff will I loose some information? I think the answer is NO but I'm not much expert in digital imaging.
    By the way I saved the same image as .tif file and the dimension on the hard disk is exactly the same: 26,3 Mb.
  4. Most .BMP files are not compressed though the standard supports RLE compression. I

    As far as I know the BMP colour table is 8 bit for each of RGB. TIF allows for 16 bits for each of RGB. You can resave your BMP file as TIF and even change the mode to 16 bit (which can help if you do successive edits) but you cannot retrieve any additional bits that the scanner captured.

    Most lab machines are essentially scanners and printers. The Fuji Frontier machines are pretty good printers but not great scanners.

    Does this help ?
  5. Open the image and save it as a TIFF with RLE or ZIP encoding and it should get smaller. If you change to 16 bits it will get bigger.
  6. RLE and ZIP are both lossless compression. The only downside is that the file takes a little longer to open. You lose no information going from BMP to TIFF.
  7. Thank guys!
  8. BMP, TIFF and JPEG files (and others) are image files - composed of pixels rather than vectors. BMP files are a relatively simple format adopted by Microsoft. BMP files describe the content of each pixel in three colors, but contain no information related to size or color space, and are seldom used. They are usually mapped to the screen on a pixel for pixel basis, making it hard to view file larger than the screen size. TIFF (Tagged Image File Format) files have embedded tags which describe various modifications, including size, resolution and color space. Uncompressed TIFF files are nearly universally accepted by service bureaus. PSD (native Photoshop) files can contain vast amounts of information, including layers and extra channels (many of which can be saved in TIFF files too). JPEG files have informational tags like TIFF files, but are limited to a single layer, 8 bits/channel, and are subjected to varying degrees of lossy compression (some information is discarded to save space). JPEG files are also nearly universally accepted, and often preferred by minilab services for printing.
    All files opened in Photoshop are PSD files while in the open state, and can be saved as PSD or other formats on closing. While PSD files are portable between Photoshop users, PDF (Adobe Acrobat) files can contain the same information in a more compact form, and can be read by anyone with the latest version of Acrobat Reader. PDF files are becoming the lingua franca of service bureaus, commercial and governmental documents, and for proofing by wire.
    qv. Adobe Photoshop CS2 for Photographers, Martin Evening, p556ff, for more information on these and other formats in common use. You will need an earlier edition to find anything about BMP files.
  9. My experience seems to run counter to some of the above responses. BMP files are very nearly the same size as an uncompressed 8 bit TIF, and you can convert between them without any quality loss. But TIF offers more options like lossless compression and 16 bit, and is far more common for photography.
  10. While working part time at a large print shop some years ago, I have always gotten perfect results with the Windows BMP format. This is probably due to its relative simplicity of indexing colors from a standardized Windows palette whereas TIF or PS files sent to us would produce something that was not quite to their expectations. These formats were later required by us to produce a proof print being sent to the customer for color calibration approval. Also, I'm not exactly sure but it might be because most of our large printers (Oce Roland Mutoh HP NUR) came with their own dedicated Windows print controllers which I assumed, would naturally understand its own BMP format. But BMP however, is pretty much useless to work with in the editing stage. TIFs are much better and for that reason, I always save my originals in TIF format (or in PSD Photoshop) and export these files to BMP when sending to a printer shop. I have not had a bad print come back to me yet.

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