Why are my Tiff files so huge?

I thought raw was uncompressed, full info, how can that be because when I save to a Tiff from Lightroom the files are absolutely huge, like 40 MB or something. What is Tiff adding to these pics to make the files so big?

tiff is a natively uncompressed file format, raw files are compressed. However, tiffs can also be compressed with either Zip or LZW compression.

Yeah raw is compressed, using lossless compression.
TIFF is huge because it isnt compressed.

For each pixel, you need 24 bits of information. (That's 8 bits for red, 8 bits for green and 8 bits for blue).

There are 8 bits in a Byte. So each pixel contains 24 bits / 8 = 3 Bytes.

With 3 Bytes per pixel, an 18 Megapixel (million pixel) image will have 18 million pixels X 3 Bytes = 54 Megabytes.

As Stone 13 points out, there are some compression schemes for TIFF, but they aren't nearly as efficient as the lossy compression used in JPEG or the non-lossy compression Canon uses for RAW. Because of this TIFF files will always be large by comparison.

Note that 18 Megapixel JPEG images also contain 54 Megabytes of information even though the file size is only 4-6 Megabytes. The JPEG images are uncompressed by your JPEG viewing or editing program. They inflate to the full 54 Megabytes in your computer's video memory locations when you want to view or edit them.

guitarjeff wrote in post #15100014
I thought raw was uncompressed, full info, how can that be because when I save to a Tiff from Lightroom the files are absolutely huge, like 40 MB or something. What is Tiff adding to these pics to make the files so big?

If you save with layers they get even larger. I have a few 600MB TIFF files floating around.

Jim_T wrote in post #15101000
For each pixel, you need 24 bits of information. (That's 8 bits for red, 8 bits for green and 8 bits for blue).

There are 8 bits in a Byte. So each pixel contains 24 bits / 8 = 3 Bytes.

With 3 Bytes per pixel, an 18 Megapixel (million pixel) image will have 18 million pixels X 3 Bytes = 54 Megabytes.

As Stone 13 points out, there are some compression schemes for TIFF, but they aren't nearly as efficient as the lossy compression used in JPEG or the non-lossy compression Canon uses for RAW. Because of this TIFF files will always be large by comparison.

Note that 18 Megapixel JPEG images also contain 54 Megabytes of information even though the file size is only 4-6 Megabytes. The JPEG images are uncompressed by your JPEG viewing or editing program. They inflate to the full 54 Megabytes in your computer's video memory locations when you want to view or edit them.

this is why we need a thanks button!

If I understand JPG correctly, the file is more of a command structure that says "for the next X pixels, display them as RGB(A,B,C)", and depending on the compression factor, it will find similar colored consecutive pixels within a tolerance based on that compression factor, and make them all the same color.

I assume the Raw does something similar but has a tolerance of 0?

I haven't studied exactly how they do. Maybe that's not even disclosed, but I guess it is, since third party software suppliers do open Canon's RAW files as well.
But run length encoding is an example of a compression algorithm which doesn't loose any information, just packs it.

Great replies guys, thanks much

Jim_T wrote in post #15101000
For each pixel, you need 24 bits of information. (That's 8 bits for red, 8 bits for green and 8 bits for blue).

There are 8 bits in a Byte. So each pixel contains 24 bits / 8 = 3 Bytes.

With 3 Bytes per pixel, an 18 Megapixel (million pixel) image will have 18 million pixels X 3 Bytes = 54 Megabytes.

As Stone 13 points out, there are some compression schemes for TIFF, but they aren't nearly as efficient as the lossy compression used in JPEG or the non-lossy compression Canon uses for RAW. Because of this TIFF files will always be large by comparison.

Note that 18 Megapixel JPEG images also contain 54 Megabytes of information even though the file size is only 4-6 Megabytes. The JPEG images are uncompressed by your JPEG viewing or editing program. They inflate to the full 54 Megabytes in your computer's video memory locations when you want to view or edit them.

^

...and for each IMAGE pixel, we need 24 bits of information for the color triplet to represent 16 Million colors (8 each, R-G-B).

In comparison, in the RAW file we need 12 to 14 bits of information for a single site (also called 'pixel', but really a 'sensel') to represent a SINGLE color at 2048 or 8092 levels (Red or Green or Blue), and the Bayer algorithm uses multiple neighbor sensels to compute what RGB value to associate with that single photosite in the RAW conversion process. So, ignoring techniques like data compression, you have 14 bits per sensel vs. 24 bits per pixel, and the number of sensels in RAW = the number of pixels in JPG. Assuming 10 Million pixels, 10 Million*14 vs. 10Million*24 bits!

So there are 10 fewer bits per photosite in RAW vs. the same number of pixels in TIFF.

12 bits = 4,096 values
14 bits = 16,384 values

tzalman wrote in post #15105451
12 bits = 4,096 values
14 bits = 16,384 values

Thanks for correcting my stupidly bad binary conversion...I shudda known better, only involved in technical applications of computing for my whole career. I guess that's why I don't do it any longer, and left the software development to the engineers!

Don't forget that TIFF files can also be 16bits per colour per pixel as well. That's 48 bits or 6 bytes per pixel which can make an 18Mpix image run to nearly 103Mb.

Using 12bits per pixel for the RAW data makes sense from a data storeage perspective as you can then store two pixels worth of data in 3 bytes. This fully utilises the memory, moving to 14bits per pixel though is not so good for data storage. For efficent data handling you really need to move to 16 bits / 2 bytes per pixel, so your 14 bit camera is going to waste two bits for each pixel when it stores the data. As storage is now cheap we can afford to waste the memory to gain quite a lot of processing speed. Computers are reasonable at dealing with half bytes from 12 bit systems, but not with the way that you would need to arrange things to fully pack 14 bits into 8 bit bytes.

Alan

guitarjeff wrote in post #15100014
I thought raw was uncompressed, full info, how can that be because when I save to a Tiff from Lightroom the files are absolutely huge, like 40 MB or something. What is Tiff adding to these pics to make the files so big?

Which is one very good reason for not keeping tiff files. Keep the raw file and the various recipes for creating jpegs or tiffs if at all possible.

hollis_f wrote in post #15107269
Which is one very good reason for not keeping tiff files. Keep the raw file and the various recipes for creating jpegs or tiffs if at all possible.

Correct, keep a copy of the DPP installation at a very minimum in any photo gallery archive, so that hopefully if you have a catastrophe, you can go to the backups and bring up the software and the raws to reproduce any photo. I do that with my taxes as well, a CD that contains the tax software and all related electronic records accompany my paper items so I have almost everything to reproduce what I filed (or almost all).

Sure you can always load DPP from Canon's site, but raw file formats change over the years, and I like having versions of DPP's installation with my photos just in case.