Blue grain in black areas after export

Question

Hello! I am exporting a photo and noticed that after export, the black portion of the photo has blue grain. This blue grain does not appear in LR itself before export, and am wondering how to fix this issue?

I used various brush tools in those areas so maybe that has something to do with it? Not sure as to what could be the cause.

Thank you!

Per Berntsen · Accepted Answer

This is high ISO noise, mostly color noise it seems, but probably also some luminance noise.

You are using a camera with a small sensor at ISO 3200, so noise is inevitable.

You need to apply some noise reduction in Lightroom, and you have to do this at 1:1 view. Any other view (like Fit view) will be inaccurate and misleading because the image has been scaled. Only 1:1 gives you a true representation of the image.

You will find noise reduction in the Detail panel in Develop.

Do color noise first, drag the slider until the colored speckles disappear, then do Luminance noise.

Luminance noise reduction should not be overdone, it will give the image a "plastic" look, so it's better to have some noise in the image.

And remember, use 1:1 view.

whitefox13 · Answer

It probably is color noise, but the reason for the blue in the export is you're missing at least the blue channel. Go back to Lightroom, open the point curve of the Tone Curve panel, select the blue channel, place your cursor at the very bottom corner of the blue grid. The cursor should be a double pointed arrow cursor, not a crosshair. Make a very slight movement upward. The triangle inside the clipping warning box will be blue, stop moving upward when the triangle grays out. If the triangle is magenta then the red channel is also lost and after you recover the blue, the triangle will be red, recover that the same way. If the triangle is cyan then blue and green are lost, the triangle will be green after recovering the blue, recover that the same way. If the triangle is white, then all three channels are lost and need to be recovered. After the triangle is grayed out, Option/Alt click on the blacks slider in the Basic panel. The screen should turn white indicating there is no loss of detail in the image. If you also magnify the image there should be no blue in the image. Now export the image.

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