B&W Batch Conversion Issue

I’ve been converting 35mm B&W negatives (approaching 6000) using the following: Windows 10, LR Classic v10.1.1, NLP 2.2.0 (Color Model B+W), using a Sony A7r iii.

I have been scanning in 10-20 rolls at a time and batch converting the images. The conversion takes place after I crop each image to image only. The only adjustment I’ve made after conversion has been to change Tones to LINEAR Gamma, then syncing the Tones. At times, the batch process has been with up to 350+ images.

In doing this, I began to notice that a large collection of images were having contrast issues. I then tried converting some rolls, an image at a time. In every case, the individual images convert with a much better result than the batch output. When I compare the batch vs. individual, I do see the histogram has shifted slight to the left on the batch versions. In Lightroom, I can get the batch version to be roughly equivalent to the individual by decreasing Highlights and Blacks, increasing Whites. Of course, at this stage, the controls are reversed.

In addition, I’ve had a very few cases where the resulting image actually has some Green and Magenta appearing in the histogram. Processing these images individually outputs a true B&W image.

Is this anything anyone else has encountered?

I noticed that batch conversions can get me results that need to be re-converted. This is usually the case when the original shot is not well exposed, taken with mixed, low light and/or the histogram is only spanning a fraction of the histogram window.

Note: I mostly converted color negatives so far.


There is a known issue in v2.2 with “sync settings” not applying properly to B+W images (the settings get saved in the NLP settings, but the visual update does not happen properly until you re-open the image in NLP). This will be resolved in v2.3. Sorry for the trouble!


Thanks Nate.

The issue I’m seeing is really more about the output of the batch process vs. processing a single image. The contrast issues are present after the batch processing is complete, before I use any Syncing.

The colorization (much less frequent) is really baffling. Here are two Histograms, the first from an image resulting from a batch process (several hundred images), the second from processing the same camera image singly. The two histograms differ in the Red/Green/Blue channels. The colorized one has a depressed green channel, producing a magenta tint, and in other areas the red/blue channels are depressed, producing a green tint. The singly processed image has all three channels equal.

In all cases, I’m using the same Sony raw file (84MB files) in comparing the different approaches. I’m only looking at B&W images at this point.

Hi @plummerl - if you are seeing any kind of colorization on your black and white, see this article: Solving Image Issues | Negative Lab Pro

  1. Make sure that during conversion, you set the color model to “B+W” - otherwise the resulting conversion will not be perfectly black and white.
  2. Hit the “RESET” button (above the tone section in Negative Lab Pro) to zero out any existing settings. If your saved default settings include some kind of color toning, that toning will be applied, even to the black and white image. You can go into each of the color tabs to zero those out, or just hit the “RESET” button to zero everything out.

I’ll just add to that to hit the “save” button so that your future batch conversions will default to settings that do not have color adjustments.


Thanks Nate, however in every case the issues I’m seeing are with Color Model set to B+W! That’s what was so puzzling. In addition, I’ve never saved any settings.