Reducing noise when converting to b/w

<p>[Canon 5D2, ISOs 1600-6400, RAW conversion in DPP or ACR, processed in PS CS3]</p>

<p>I've seen some very impressive examples of high ISO photos with minimal noise "because they were converted to black-and-white," I'm told. I do a lot of such conversions, using all techniques (usually starting with CS3's Black-and-White conversion button under Image>Adjustments) but <strong>no matter what I do I can't consistently make my high-ISO b/w conversions discernibly less noisy than the color originals </strong> (when both are processed with the same NR tools, I mean).<strong><br /> </strong></p>

<p>Thoughts? Or is it a myth that b/w photos can hide noise better than color photos can? Should I be massaging one color channel more than the others?</p>

<p>Btw, I have Neat Image and Noise Ninja (I use them pretty conservatively, preferring some noise to smearing). All other factors being equal, should I be using different settings there for b/w than I do for color?</p>

<p>.</p>

<p> </p>

<p>A BW conversion may reduce color noise, but not luminance noise. If it's for viewing on screen then I'd get a little more aggressive with NoiseNinja. If it's for printing, I wouldn't worry; I lose lots of noise just by printing (esp. with BW).</p>

<p>A (silly?) way of reducing noise:<br>

Hit Crtl `, 1, 2, 3 to see the different color channels in your image. One way to minimize noise would be to use mainly the green channel when converting to B&W, since that channel has the least noise.<br>

2- It might be the case that it is best to apply NR to the image before it is converted to black & white.<br>

Try this:<br>

Use a B&W conversion plug-in like this one (that is my freeware plugin):<br>

http://www.colormancer.ca/free/download-filters/tint-plug-in.htm<br>

Make it convert only the green channel into B&W. For my plugin, set pre-saturation, red, blue weight to 0.<br>

Convert your image into a smart filter beforehand, and apply your NR plugin of choice. Then apply the B&W conversion.<br>

2- Duplicate that smart filter, and flip the order around. You can click the eye icon in Photoshop to see the difference.<br>

*This might not work with Noiseware? (Haven't checked.)</p>