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#21
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Still confused about RAW & TIF
Floyd L. Davidson wrote:
"Thomas T. Veldhouse" wrote: Little Juice Coupe wrote: The Raw file is the Raw data from the cameras sensor and in general doesn't have any of the image camera processing done to it. Which means you can change white balance after the fact without loosing image data, etc. Changing these settings are just metadata values of the RAW file [like changing the name ... it doesn't affect the actual image data] and these values are applied during conversion to RGB (or whatever). The Nikon D2x uses a 4 channel output sensor and does white balance correction at the analog level *before* the image is digitized. Give me a reference to that please. I do NOT believe that to be the case ... there is simply no "analog level" to apply white balance too. A 16 bit TIFF formatted file is easily able to contain all of the data available in a 12 bit NEF file. I indicated that they would be similarily sized files for the same bit-depth. They would. -- Thomas T. Veldhouse Key Fingerprint: D281 77A5 63EE 82C5 5E68 00E4 7868 0ADC 4EFB 39F0 |
#22
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Still confused about RAW & TIF
Scott W wrote:
The raw filewill me much smaller since its format is much more efficient. Take a 8 MP camera, the in the raw file there are 8,000,000 pixels each of which needs only 12 bits of data, therefore and uncompressed raw file should come in right about 12 MB, with lossless compression this shrinks to between 8 to 10MB. A tiff file from this same camera will have three colors / pixel (note the raw file only has one per pixel) and it will use 16 bits / color or 48 bits per pixel compared to 12. When I convert to 48 bit tiff files the resulting file is right around 48 MB in size, which is why I don't like to keep the tiff fills around. Only if compressed will you see a difference [minus the metadata]. Data is data. RAW is only smaller than TIFF for two reasons; the first is that there is often compression applied (TIFF can also be compressed, but often is not), and second is that typically RAW is 12-bit and TIFF is 16-bit. There is no reason you can't have a 12-bit RAW (in fact, that is basically what you get when you convert to DNG format as DNG format is based upon the TIFF format and DNG is a true RAW file, preserving the linear data with or without lossless compression). -- Thomas T. Veldhouse Key Fingerprint: D281 77A5 63EE 82C5 5E68 00E4 7868 0ADC 4EFB 39F0 |
#23
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Still confused about RAW & TIF
Thomas T. Veldhouse wrote: Scott W wrote: The raw filewill me much smaller since its format is much more efficient. Take a 8 MP camera, the in the raw file there are 8,000,000 pixels each of which needs only 12 bits of data, therefore and uncompressed raw file should come in right about 12 MB, with lossless compression this shrinks to between 8 to 10MB. A tiff file from this same camera will have three colors / pixel (note the raw file only has one per pixel) and it will use 16 bits / color or 48 bits per pixel compared to 12. When I convert to 48 bit tiff files the resulting file is right around 48 MB in size, which is why I don't like to keep the tiff fills around. Only if compressed will you see a difference [minus the metadata]. Data is data. RAW is only smaller than TIFF for two reasons; the first is that there is often compression applied (TIFF can also be compressed, but often is not), and second is that typically RAW is 12-bit and TIFF is 16-bit. There is no reason you can't have a 12-bit RAW (in fact, that is basically what you get when you convert to DNG format as DNG format is based upon the TIFF format and DNG is a true RAW file, preserving the linear data with or without lossless compression). You are missing the big reason, 1 color / pixel for raw vs. 3 colors / pixel for tiff. Scott |
#24
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Still confused about RAW & TIF
Scott W wrote:
You are missing the big reason, 1 color / pixel for raw vs. 3 colors / pixel for tiff. True ... but there are Red, Green and Blue pixels, each getting 12-bits of linear data, which makes up one pixel [three colors] in TIFF. In fact, for some reason, I believe Bayer sensors have two green pixels for every RGB pixel in TIFF. -- Thomas T. Veldhouse Key Fingerprint: D281 77A5 63EE 82C5 5E68 00E4 7868 0ADC 4EFB 39F0 |
#25
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Still confused about RAW & TIF
Thomas T. Veldhouse wrote:
Scott W wrote: You are missing the big reason, 1 color / pixel for raw vs. 3 colors / pixel for tiff. True ... but there are Red, Green and Blue pixels, each getting 12-bits of linear data, which makes up one pixel [three colors] in TIFF. In fact, for some reason, I believe Bayer sensors have two green pixels for every RGB pixel in TIFF. I take that back ... I am sure green is probably just weighted doubly during conversion. -- Thomas T. Veldhouse Key Fingerprint: D281 77A5 63EE 82C5 5E68 00E4 7868 0ADC 4EFB 39F0 |
#26
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Still confused about RAW & TIF
Thomas T. Veldhouse wrote: Thomas T. Veldhouse wrote: Scott W wrote: You are missing the big reason, 1 color / pixel for raw vs. 3 colors / pixel for tiff. True ... but there are Red, Green and Blue pixels, each getting 12-bits of linear data, which makes up one pixel [three colors] in TIFF. In fact, for some reason, I believe Bayer sensors have two green pixels for every RGB pixel in TIFF. I take that back ... I am sure green is probably just weighted doubly during conversion. No, there are twice as many green as red or blue on the filter array. It looks like RGRGRGRGRGR GBGBGBGBGBG usually. |
#27
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Still confused about RAW & TIF
"Thomas T. Veldhouse" wrote in message news Your above statement isn't correct. There is no way to know which has more information based upon file format. Equal sized uncompressed TIFF and RAW with the same bit depth should be similarily sized. That's dead wrong. In general the TIF file will be about three times larger. rafe b www.terrapinphoto.com |
#28
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Still confused about RAW & TIF
Thomas T. Veldhouse wrote: Scott W wrote: You are missing the big reason, 1 color / pixel for raw vs. 3 colors / pixel for tiff. True ... but there are Red, Green and Blue pixels, each getting 12-bits of linear data, which makes up one pixel [three colors] in TIFF. In fact, for some reason, I believe Bayer sensors have two green pixels for every RGB pixel in TIFF. It's interpolated. In reality, if you have an 8000000 pixel camera, each of these pixels receives either red, green or blue light. Thus, 12 bits per pixel in the raw data (each pixel records one colour). What conversion from raw to eg tiff does is, basically, to take these and interpolate so that each pixel is assigned a colour (not just a value for r, g or b, but one for each). Thus, an 8mp raw uncompressed file will be around 12MB, while an 8mp 8-bit (per channel, as 8-bit usually signifies) tiff will be around 24MB (and 48MB if 16-bit). If you don't believe me, google for IRIS, download it and look at a raw file. Or google for demosaicing, I'm sure you'll get lots of hits. Whether the format is linear or not is completely irrelevant to the size of the files; it only has to do with their interpretation. |
#29
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Still confused about RAW & TIF
"Thomas T. Veldhouse" wrote in message .. . Scott W wrote: You are missing the big reason, 1 color / pixel for raw vs. 3 colors / pixel for tiff. True ... but there are Red, Green and Blue pixels, each getting 12-bits of linear data, which makes up one pixel [three colors] in TIFF. In fact, for some reason, I believe Bayer sensors have two green pixels for every RGB pixel in TIFF. But the fact is, in a so-called "6 megapixel" camera, there are only 6 million sensors, distributed between Red, Green and Blue. Green gets 2X as many pixels as either Red or Blue, so in this example, 1.5 million (each) of Red and Blue, and 3 million green. In the equivalent TIF file there will be 18 million values (6 million per color.) Each reading (in the sensor) may be up to 12 bits, but the lossless compression will reduce the overall storage by 20-30%. Thenet result for a RAW file is roughly one byte per pixel. It's the RAW converter program that does the interpolation from RAW to TIF, and that's where the file size gets tripled. rafe b www.terrapinphoto.com |
#30
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Still confused about RAW & TIF
rafe b wrote: "Thomas T. Veldhouse" wrote in message news Your above statement isn't correct. There is no way to know which has more information based upon file format. Equal sized uncompressed TIFF and RAW with the same bit depth should be similarily sized. That's dead wrong. In general the TIF file will be about three times larger. Well if the tiff file is 16 bits/color it would be about 6 times larger. The loss using an 8 bit tiff instead of a 16 bit one is small but sometimes it does matter. Scott |
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