D750 blotchy blacks

[radicalgel]

<p>I'm noticing some patchiness in the blacks when I view images at 100% on the screen on the D750. I see a similar problem when previewing the image in the library module of Lightroom. However, the moment I go into the develop module the problem disappears and I have a perfect image. I'm shooting in RAW so I'm guessing issue is with the way the lower res JPEG previews are being compressed and rendered. Can anyone else confirm if they have this issue? I've attached and image of this problem. You can clearly see the pixellation zoomed in at 100% on a black region of the image.<br>

<br>

<img src="http://4.static.img-dpreview.com/files/p/TS560x560~forums/55419544/84c3fb44cb6e43f1b5e6ff30ae06c108" alt="" width="560" height="418" /></p>

[andylynn]

The blotches are a jpg artifact resulting from insufficient numbers of levels being assigned to the darks by the jpg

processor in the camera. (It's been posterized.) When you vie the image on the camera's screen you're looking at a jpg

preview created by the camera based on current camera settings. The same preview is what's initially displayed in

Lightroom. After Lightroom has had time to process a preview based on its own settings, it uses that instead, which is

why the blotches disappear.

[ShunCheung]

<p>Excellent explanation from Andy. That image of the back LCD of the D750 looks like an extreme magnification of a tiny area from the original frame. I would expect some (maybe plenty of) posterization under such magnification: http://en.wikipedia.org/wiki/Posterization<br>

What is important is that the full RAW file is good.</p>

[Landrum Kelly]

<blockquote>

<p>What is important is that the full RAW file is good.</p>

 

</blockquote>

<p>Yes, indeed. This is the camera I am buying after I do my next bank job.</p>

<p>--Lannie</p>

[ShunCheung]

<blockquote>

<p>This is the camera I am buying after I do my next bank job.</p>

</blockquote>

<p>What is a "bank job"?<br>

You are robbing a bank to buy a D750? I don't think it is a good idea to pre-announce your plan on photo.net.</p>

<p>:-)</p>

[rodeo_joe1]

<p>The LCD display on the back of a DSLR, like most "cheap" LCD displays probably only uses 6 bit colour depth. So even though a JPEG might store 256 brightness levels, that's rendered down to only 65 after the LCD gets its hands on the image. Most low-end LCD televisions are also only capable of showing 6 bit colour, hence the stepped transition of tones that are often seen on them, for example in what should be smooth skies.</p>

<p>Plus the crazy sRGB standard has a log-to-linear kink in its gamma curve at around brightness level 12 (decimal). The things that happen when you get a committee designing things! You could try switching your colour space to Adobe RGB, which uses a purely log gamma of 2.2, and see if the posterisation gets any better.</p>

[radicalgel]

<p>Andy is spot on. Thank you for the explanation. Looks like the camera creates a low quality JPG preview of the RAW. This issue is absent when shooting JPG fine since you are viewing the actual, high quality image in this case. Thank you the help guys. Happy shooting. </p>