file size--k10D

[elnoralouisa]

This has been going on for awhile--and I thought it was my software. I

finally checked my camera card. My files are usually between 2.7 and 4 (at

the very most megapixels. I have the camera set to 10M and to *** (best).

What good is a 10M camera, if I can usually getting pics at 3M. This is

becoming a problem as I am now doing pictures that I want to enlarge, and I

know if I crop at all, I am really losing things!

[matt_murtagh]

You are shooting JPEGS, these are a compressed image format and so the file size come out a lot smaller than 10M, there is still 10M of information there, you are not losing anything!

[danield]

Debbie, you are confusing Mega-Pixels (as in pixels in the sensor) with Mega-Bytes (as in size of Jpeg files). Jpeg files contain compressed information, even a 3 megabyte jpeg can contain 10 mega pixels of image. Jpegs lose some information through compression but not that much really.

 

Otherwise, shoot in RAW mode and you won't lose anything. But, seriously, take some time to read about pixels and bytes and jpeg images.

[j_anon]

Or better yet (what an unusual unique concept)....READ THE MANUAL

[elnoralouisa]

I did! Gee, sorry for asking a question. I checked the manual to make sure

I had everything set right, which I did.

Thanks to the other person that explained it, to which I said oh yeah,

that's right........

(yeah, I know, I should change to RAW, just haven't.

 

Debbie

[odin1]

Hi Debbie!

There is a confusion (and you are not the only one to be confused about it...) between camera resolution and picture/file resolution, actually camera's resolution should be named otherwise because it's expressing *dimensions* and not *pixels* per inch. In short your camera's resolution (10 MP in your case) is expressing the dimensions of the picture you have taken (x pixels x y pixels=10.000.000 pixels which can be translated in k inches x z inches), the other resolution expresses the number of the pixels you have in a square inch (72 ppi is the original resolution your files are recorded in your memory card). Printing dimensions and resolution (ppi) are related, when you are lowering the ppi number in PS you are getting a bigger picture (but less detailed) to print, when you are rising the ppi number you are getting a smaller picture but with grater detail.

As for your small files, you are obviously shooting in JPEG format which is a compressing format, turn to Raw and you'll have much bigger files.

Best regards

Odin

[andrewg_ny]

Debbie: The images you capture have pixel dimensions of 3,872 x 2,592 = 10,036,224, or just over 10 million (mega) pixels. As you've seen this does not correlate directly to file size. For each pixel, there would be 24 bits of information (8 bits each of red, green, and blue)...but additional data in the file (EXIF, headers, etc.) and JPEG compression hugely alter and muddy these calculations.

[mountainvisions]

Debbie,

<P>

A JPEG is a compressed file, it's only 8 bits and it's lossy.

<P>

The camera decides what stays and goes to make your 56MB tiff into a 4MB JPEG.

<P>

Honestly, while it might be a pain, I highly recommend shooting RAW to get the most out of every shot.

<P>

If you use RAW, you get unfinalized 16 bit images, if you shoot AdobeRGB you further expand the gradient between color changes, effectively expanding your cameras dynamic range.

<P>

However, this requires 2 additional steps on your part.

<P>

1) converting from RAW to TIFF or JPEG (i recommend tiff all the way till your final web resize because, again, TIFF is an uncompressed, lossless file format)

<P>

2) converting from TIFF to JPEG in PS. TIFF's are simply too big to email or share on the web. However, a 100% JPEG at 1000pixels is between 400-800K in most cases.

<P>

Now the advantages of RAW:

<P>

1) forget about the WB in the field. Just get a good exposure and deal with WB fine tuning at home.

<P>

2) you have archival files (shoot DNG) from the start that can be altered but not destroyed (even a uncompressed TIFF, looses quality as you alter the pixels) and you can go back and back to it and redo WB, sharpness, Noise Reduction, ect without damaging the file.

<P>

3) you can upsize for free and fairly without much penalty. My test of RAW upsizing vs. TIFF upsizing with Photoshop have shown better quality, almost no loss of IQ to bump the MP cound up a sensor size.

<P>

For instance I regularly bump my ist D 6MP up to 10MP with 0% visible loss of quality. I'd say this method is nearly as good as the program Genuine Fractals which the pros use to generate large prints from smaller cameras.

<P>

In anycase, unless you changed the JPEG size to less than 10MP your camera is getting 10MP images, it's just the file size that you are looking at. And for good reason, the whole point of a JPEG is file portability, NOT IMAGE QUALITY.

<BR>

<a href="http://feeds.feedburner.com/%7Er/MountainVisions/%7E6/1"><img

src="http://feeds.feedburner.com/MountainVisions.1.gif"

alt="Mountain Visions: The Wilderness Through My Eyes"

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[thebs]

Debbie -- Here are the bullets concepts ...

 

- Number of pixels is the not the same as file size

 

- There is more than 1 byte per pixel, because each pixel is 24-bit (8-bit channel) to 36-bit (12-bit channel) color

 

- That means number of bytes is 3-4.5x the number of pixels. E.g., 10MP "RAW" is actually 45MB!

 

- Compression affects file size

 

- Lossless compression, such as RAW, TIFF, etc... only compresses the pixels to a point where they can be "extracted" back to their "original" quality. The Pentax sensor is capable of 12-bit color channels -- 36-bit, or 4.5 bytes per pixel, color. That why they are 10MB+.

 

- Lossy compression, such as JEPG, compresses by changing the pixels, merging like colors, and causes other loss. Different levels of "lossy" compression are why you have 3MB, 1.5MB or even smaller files. JPEG itself is also only 8-bit color channels -- 24-bit, or 3 bytes per pixel, color.