Monday, September 24, 2012

Lightroom 4. Banding. Artifact. Posterization. Canon 5D Mark III.

Banding. Posterization. Lightroom. Canon 5D Mark III

It's like the perfect storm. Within the last half a year or so, I purchased a new iMac, a Canon 5D Mark III and Lightroom 4. I didn't do a software upgrade.   Throw a very slow AT&T internet connection and you get a gail force/tsunami/earthquake all in one.

I have HORRIFIC banding in some of my photos and for the life of me, I couldn't pin-point what exactly was the cause.  With all the above variables, I had to discover by process of elimination what the root of the banding was.  Was it in Lightroom 4? Was there a problem with my new Canon 5D Mark 3?  Was it a memory card issue?   Was my iMac screen not calibrated?  Did I forget to do an Adobe Software upgrade?  Was it a Camera Raw/Lightroom 4 issue because it doesn't correct for artifact.   Is it me shooting with a low ISO?  My goodness so many variables.

I tried everything. In Lightroom 4 I changed all the parameters to try to determine what the cause was. I changed the various values, one-by-one and exported the photo to see more banding or LESS banding. I was hoping for ZERO banding.

I changed the RGB value on my iMac to no avail.   Was it regular RGB or RGB (1998?)

I then looked at the original CR2 file that I uploaded to Lightroom 4 and compared it with the same file, but this time uploaded to Photoshop CS6.  Lightroom 4 for some reason showed a little more banding, yet, Photoshop still had a little banding in the original, unretouched, un-post-processed file.

Then I went online to search the web for solutions. I typed in:
Banding, Lightroom 4, Canon 5D Mark III.

I also typed in just:
Banding, Lightroom 4

Banding, Lightroom 4, CS6

One solution was to adjust the "grain" in the develop mode of Lightroom 4. And by golly it looked like the banding visually disappeared.

Due to the high volume of photos that I upload, I set the export quality of my photos from around 100----that takes forever and a day to upload photos, to around 20.  With the quality set to 20, the upload time is diminished and THAT makes impatient me....HAPPY.

Just for a lark, I decided to up the quality in the export mode from 20 to 50. And you guessed it. The banding totally disappeared.

SOLUTION: When exporting files from Lightroom 4 to your desktop or a folder, instead of setting the quality to a mere 20 just to speed up the export time (consequently causing banding)  simply set a higher quality number and wait for the files to upload a little  (usually a LOT) longer.

According to source WIKIPEDIA:

Posterization of an image entails conversion of a continuous gradation of tone to several regions of fewer tones, with abrupt changes from one tone to another. This was originally done with photographic processes to create posters. It can now be done photographically or with digital image processing, and may be deliberate or may be an unintended artifact of color quantization.


The effect may be created deliberately, or happen accidentally. For artistic effect, most image editing programs provide a posterization feature, or photographic processes may be used.
Unwanted posterization, also known as banding, may occur when the color depth, sometimes called bit depth, is insufficient to accurately sample a continuous gradation of color tone. As a result, a continuous gradient appears as a series of discrete steps or bands of color — hence the name. When discussing fixed pixel displays, such as LCD and plasma televisions, this effect is referred to as false contouring.[1] The result may be compounded further by an optical illusion, called the Mach band illusion, in which each band appears to have an intensity gradient in the direction opposing the overall gradient. This problem may be resolved, in part, with dithering.

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