"Image Quality": JPEG normal vs. JPEG fine

[tsaraleksi]

Quote: Originally Posted by kundalini

Nikon does offer a Compressed NEF file format on the D300 (and a few other models I believe).

Interesting-- how does that work? I assume it's not the same as the sRAW stuff Canon has brought out (ie smaller res raw files).

[kundalini]

Quote: Originally Posted by tsaraleksi

Interesting-- how does that work? I assume it's not the same as the sRAW stuff Canon has brought out (ie smaller res raw files).

I will quote from Thom Hogans Complete Guide for the D300:

Quote:

The D300 supports two types of compressed NEF files. One version is said to be “lossless” (and labeled as such in the camera), while the other is said by Nikon to be either “virtually lossless” or “visually lossless”, meaning that results visually indistinguishable from those that would be produced by the original data can be recovered.

Lossless compressed NEF truly lossless
Compressed NEF visually lossless

“Visually lossless” isn’t quite the same as “lossless”. In the truly lossless version the original data is recovered exactly when the data is later uncompressed, so we don’t have to worry about or discuss further what happens with the data in the Lossless compressed NEF option.

In the “visually lossless” version (Compressed NEF) you get some of the original data back (in the shadows and some mid-tones), but the highlights are posterized in a way that is consistent with the human vision’s capabilities. We do need to discuss how this works, as it ca produce visual effects in your images.

I’m not sure I’d term the methodology Nikon uses for the visually lossless format as “compression”, but here’s how it works: when photosite data comes off the ADC, it has 12 or 14 bits of value to it. Let’s use 12-bits to keep things simple. A 12-bit value from the ADC of 0 would represent “no data”(black), a value of 4095 would represent “saturation”(white). If that was the way we stored the data, we’d need 12 bits to store each photosite’s data. In order to reduce storage size, the D300 (and other Nikon DSLR bodies) include a special method of “compressing” NEF data (Compressed NEF set via the D300 SHOOTING menu) which works as follows:

· Shadow and low mid-range values as passed on as is.
· High mid-range and highlights values are split into groups (essentially, neighboring values are rounded to a central value; for example values of 1023, 1024 and 1025 might all be grouped together and stored as a single value). The manner in which this is done isn’t linear. The last possible group value (almost white) has more adjacent values in its group than the first. This non-linearity is designed to correspond to the way our eye is able to distinguish between bright tones.

Thus, there are significantly fewer than 4096 values possible in the scheme for a 12-bit data and significantly less than 16384 values for the 14-bit data. The resulting “compressed data” is further compressed using a somewhat traditional method that looks at adjacent differences and is truly lossless; the final data is also packed across byte boundaries for space efficiency. The result is that the 12 bits of original data stores in about 6 bits (and 14 bits of original data stores in about 7 bits).

Interested in how to get the 12 bit of data back?

[McKaso]

A few good articles with samples to show the the effects of compression on a jpeg file and how it compares to raw files.

Steve's Digicams - Tech Corner - October 2004

Jpeg Compression - photo.net

JPEG Vs. RAW: The Advantages and Disadvantages Explained - - PopPhotoJanuary/February 2006

RAW vs JPG

[dtornabene1]

Quote: Originally Posted by dtornabene1
While tsaraleksi answered your question, I have one for you. Why are you shooting in JPEG? Always, I mean ALWAYS shoot RAW. Now if you are using a camera without this ability, ignor my advice.

-Nick


[quote=ANDS!;1486431]Even when shooting fast action sports? Theres a time and place for every image format. A time and place.

Get a faster memory card or camera. Always shoot in RAW.

Compression should only be a concern when dealing with pp (post production) and not always then. There are many, albeit higher-end, labs that will take popular RAW formats.

-Nick

[Overread]

Quote: Originally Posted by majorpayne66

Not trying to jack this thread, just thought I would jump in.
I am shooting JPEG fine because I want to learn photography first and have little interest in learning to edit. I am just starting to edit some images with PP and am happy for now.. Sounds like I should move to JPEG+RAW for future editing. Is this right ? Can you elaborate on what JPEG+RAW does?

JPEG+RAW will save you 2 copies of every photo you take = one will be a JPEG verion and the other will be a RAW version. Thus you will be able to work with both - thus meaning that in the future when you can and want to edit in RAW you can come back and re-edit older photos. However the downside is that this does eat up more card space so you can take fewer shots on a set card size. YOu also have to store the photos on your computer as well.

As for the JPEG vs RAW argument there are times when one wants to have photos that don't need editing to be usable, when they don't have space for enough RAWs on their memory card, when they don't like having to edit every shot or when speed of processing is required.

JPEG allows this to be the case and thus has a purpose as a save formate - for many pros and amteurs the advantages of RAW nearly always win out over JPEG but one has to appraoch the choice with an understanding as to why they have chosen to use a mode rather than just blindly following the doctrine that one is better over the other

[majorpayne66]

Thanks as always Overread. Sooooooooooooo, sounds like I should use it as just another setting. Likley wont use RAW for say a Birthday party, but I should use RAW when I head up to the mountains.

[sabbath999]

Quote: Originally Posted by majorpayne66

Sounds like I should move to JPEG+RAW for future editing. Is this right ? Can you elaborate on what JPEG+RAW does?

In addition to what everybody else has said, JPEG + RAW gives you a unique look at what your camera's processors are doing to the JPEG files.

I do find it humorous when my photography friends spend hours trying to make their RAW images look as good as the JPEG companion shots...

Obviously, RAW can save you when you miss (or in some situations where you have multiple white balance issues, like for example underwater photography with flash and an ambient background).

More often than not when I shoot RAW + JPEG I just use the JPEG because my camera nailed it in the first place... EXCEPT when I use my D40, which annoyingly only uses basic compression on JPEGS when shooting JPEG + RAW and there is a huge difference between Basic and Fine on that camera.

[majorpayne66]

Thanks for the input Sabbath, Now that I know when to use RAW and JPEG I think it would be beneficial just to leave it in JPEG+RAW, especially with the cost of 8gb cards dropping in price. I picked one up a couple months ago for $35. That is cheap insurance.
Having options is good!