Jump to content
pranfeuri

What is the difference between shaddows and dynamic range

Recommended Posts

Most of the times things like these have been spoken about before, using the search engine could help

 

http://www.fuji-x-forum.com/topic/5532-the-use-of-dynamic-range-highlight-and-shadow-tones/

 

you will find what you look for contained in these articles, 

 

http://lxcellent.blogspot.nl/2012/12/using-fuji-x-e1-tone-controls.html

 

http://www.fujirumors.com/how-to-expand-dynamic-range/

Share this post


Link to post
Share on other sites

It's not a stupid question Pranfeuri. In a nutshell then, here goes. Dynamic range is a term used in electronics. In a camera it is used to describe the brightness range from the deepest shadow tone that can be distinguished from noise to the brightest tone that can be recorded before the sensels become saturated and cannot convert any more photons. In ye olden days when I used film the equivalent was known as the films latitude. An analogue to digital converter is used in the camera to digitise the output from the sensor and can usually give a 14 bit wide digital output. Jpegs are only 8 bit so they cannot include all those tones. However 8 bits are enough to describe all the tones that a monitor, tablet etc can display or a that print can reproduce. Therefore we have the opportunity to compress the 14 bits into 8 bits using what is known as the tone curve. The algorithm in the camera does this for us but may need altering for some images. The DR and shadow and highlight settings in the Fuji cameras can be used to do this. Basically the DR settings underexpose so as not to blow the highlights and boost the mid and shadow tones to fit in. The shadow and highlight adjustments change the tone curve to make them darker or lighter as required. Of course if you use raw then you can decide afterwards how to fit the tones in. That is one of the main advantages of raw. With the latest sensors it's amazing how much detail can be rescued from the shadows before noise becomes a real issue.

Share this post


Link to post
Share on other sites

Most of the times things like these have been spoken about before, using the search engine could help

 

http://www.fuji-x-forum.com/topic/5532-the-use-of-dynamic-range-highlight-and-shadow-tones/

 

you will find what you look for contained in these articles, 

 

http://lxcellent.blogspot.nl/2012/12/using-fuji-x-e1-tone-controls.html

 

http://www.fujirumors.com/how-to-expand-dynamic-range/

I did use the search engine and while those links discuss both shadow and HDR, I still found it hard to understand how they differ from a technical pov.

Just explaining what each does, is something I would do on an exam, where I don't realy grasp the subject in depth and just repeat what I've red in my textbook without linking the two together.

Share this post


Link to post
Share on other sites

"Shadow" settings adjust gamma near the dark end of the luminance range. This is typically used to artificially increase luminance in low-luminance areas so you can see more detail in dark areas when the image is reproduced. Shadow enhancement can be applied to any photograph, even photo's taken with "DR" enhancement. Those settings usually just re-map gray levels. For example, gray levels 1, 2, and 3 may be re-mapped to gray levels 2, 4, and 6 making them artificially brighter.

 

Dynamic range is supposed to be an increase in the sensor's range of counting photons. That is, if a pixel element in the sensor needs 10, or more, photons to be not-black and 10,000, or fewer, photons to be not-white (saturated), the dynamic range is 1000:1. Now, say that some new sensor may be able to read only 5 photons for not-black and can accept 50,000 photons for not-white resulting in 10,000:1 dynamic range. True dynamic range is a function of the photo-receptors on the camera's sensor.

 

Please note that dynamic range has nothing to do with bit-depth - the number of gray levels. Bit-depth simply divides the sensor's operating range of detectable luminance into gray levels. A sensor with 1,000,000:1 dynamic range can have an 8-bit per color conversion or a 14-bit per color conversion but you should expect the 8-bit to show gradations, or lines, where the photon count breaches the next gray level. Spacial dithering can help smooth "chunky" gray levels but the best way is, obviously, to add more bit-depth, which divides the sensor's luminance range into finer and finer slices.

 

There are ways of fudging this, though, so beware of the difference between true dynamic range and "features" that call themselves Dynamic Range, or DR. Fujifilm has been adjusting gain in pixel elements so that, even if the element's range is small, the range can be moved, shifted, so that some elements are "tuned" to be more sensitive and some are "tuned" to be less. This technique effectively increases a picture's dynamic range at the cost of... spacial dithering; that is, half the pixels scattered throughout the image may be exposed more, leading to blooming in bright areas just to capture detail in dark areas, while the other pixels might be less exposed to preserve detail in bright areas at the cost of losing detail in shadows.

 

Using a DR setting sprinkles darker pixels in with brighter ones to (theoretically) increase the dynamic range of the picture (but not individual pixel elements). (I said, "theoretically," because the increased dynamic range must be saved in the picture, then reproduced on some media capable of showing it.) There is nothing inherently wrong with this approach and it can actually aid in giving a photo film-like grain.\

 

Of course, there is another way to increase dynamic range: Take two photographs with different exposure settings and overlay them. That is the common "HDR" stuff you read about. Typical HDR photography increases dynamic range by using temporal dithering (in a very simplistic sense).

 

Shadow enhancement can be applied to any photograph, even photo's taken with "DR" enhancement. Those settings usually just re-map gray levels. For example, gray levels 1, 2, and 3 may be re-mapped to gray levels 2, 4, and 6 making them artificially brighter.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...