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Old 12th March 2011
toady
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Re: Need help on E-420 RAW files

Quote:
Originally Posted by Ian View Post
No that doesn't make sense.

MP = mega pixels, or the number of image pixels

MB = megabytes, or the quantity of bytes in the file

Unless you crop or resize the image the number of pixels in an image file remains constant.

In uncompressed form the number of bytes in a 24-bit RGB image (8-bits per byte and 3 bytes in all, so 3x8=24) the number of bytes is 3x the number of pixels and then divided by a million (or 1024x1024).

JPEG, though, is compressed, so the number of bytes can vary significantly, even though the number of pixels stays the same.

With a 10MP camera the maximum possible file size is 30MB (3x10MP). With JPEG compression the file is normally well below 10MB, but if - as Toady suggests - you post process, you can increase the file size because compression is less effective. This can be because of increasing sharpness and even adding noise, which is a technique for adding depth to some types of image. The noisier the image the less it can be compressed.

Ian
thanks ian
my ignorance not having used raw a lot or even knowing the information
i checked my raw files and they are indeed 10.1 Mb
the corresponding processed tif is 33.6
and the final jpeg..13.7

this is all new to me
cheers
geof
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