Talk to any old school photographer or those with lots of experience from the film days. They would most likely tell you that scanning their film negatives gives you TIFFs that are essentially the same things as a RAW file. But is it really? I interviewed the legendary Chuck Westfall from Canon USA about this. Here’s what he had to say.
Chris: Tiffs are lossless images, but so are RAWs. How do they differ?
Chuck: Here are some of the main advantages of Canon RAW (.CR2) vs. TIFF and JPEG:
Non-destructive editing: The original data remains intact no matter how many times it is rendered into a usable image file.
Canon RAW data is recorded at 14 bits per channel, resulting in superior tonal gradation compared to the 8-bit rendering limit mandated by the JPEG standard. (RGB TIFFs can be stored in 8-bit or 16-bit format.)
Numerically lossless compression is used to reduce .CR2 file size, but image quality remains completely intact with no compression-related artifacts. ([The] Major advantage in camera performance and storage efficiency compared to TIFF.)
No tone curves or sharpening are applied when .CR2 files are recorded, thus allowing full manipulation of these properties when images are rendered.
Canon RAW data is recorded in sYCC color space, which has a much larger gamut than Adobe RGB or sRGB. This allows rendering into various color spaces.
Chris: Which one is truly a digital negative?
Chuck: I would say “neither.” In my opinion, RAW image data is more accurately described as a digital latent image in the respect that it has not been processed into a usable image until it is rendered into a new file and stored in a different recording format, such as TIFF or JPEG. In the world of film recording, the term “negative” refers to an image that’s been processed to a certain degree.
Chris: What would the difference be in the editing process when using a program like Lightroom or Photoshop?
Chuck: RAW image data requires an extra step of conversion compared to TIFF files, but the trade-off is that RAW data typically has the advantages of a larger native color space and potentially greater bit depth as well as completely adjustable white balance, sharpening, etc. Another important difference is that RAW image data supports non-destructive editing, in other words RAW image data remains intact after editing, whereas most image editing done to TIFF files such as contrast, sharpening and saturation enhancement cannot be undone once saved.
Chris: Back in the earlier days of digital, some cameras shot TIFFs. Why has this been phased out?
Chuck: Mike McNamara and I covered this in an article that’s currently posted on the Canon Digital Learning Center. Here’s the relevant excerpt:
“Some readers may wonder about in-camera TIFF files, especially as an alternative to unprocessed RAW files. After all, most RGB TIFF files are uncompressed, finished, and ready-to-use. However, there are several downsides to the idea of in-camera TIFFs. For one thing, standard in-camera TIFF files are typically limited to 8 bits of information per pixel instead of 12 or 14 bits, so they are inferior to RAW image data in terms of tonal gradation. Another downside to uncompressed TIFF files is file size: With a 12 million pixel camera, an 8-bit RGB TIFF image would produce a file size of about 36MB on the memory card for every shot — with none of the added flexibility or additional tonal information available in even a 12-bit RAW file. If the camera offered the option to record 16-bit TIFF files, the situation would be even worse because the file size would double to 72MB per image! These huge files would drastically impair camera burst performance and squander memory card storage capacity, with less image quality compared to RAW files. As a result, TIFF recording is rarely an option in modern digital cameras. However, TIFF is still the preferred recording format for storing post-processed images.”
Chris: Let’s say that I were to shoot 120 film and scan it in using something like the Canoscan 9000F what kind of versatility in editing could I expect?
Chuck: Generally speaking, film scanning is a labor-intensive process compared to digital capture. That said, a high-quality film scanner is capable of producing an excellent digital image that can be edited to the same extent as any other TIFF file. However, no scanner that I’m aware of supports RAW capture.
Correction: the Nikon Coolpix scanners can scan to RAW NEF.
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