B&W Conversions,avoiding posterization

[richard_lyman1]

<p> Hi Everyone,<br>

I have been doing some B&W conversions and am having an issue with posterization. Generally my workflow is to import the RAW file from Bridge (I'm using CS4) and convert it to 16 bit and then use the channel mixer. I'm trying to achieve an almost infra-red look with the sky very dark almost black. Most of the time I'm doing landscapes and since there is often not a cloud in the sky here in SW Florida in the dry season I'm getting some very bland backgrounds.</p>

<p> My understanding is that converting to 16 bit and editing with the channel mixer is the best way to avoid this, but I still get very bad posterization affects. I am pushing the limits I realize with the blue channel set as black as possible. I have tried converting to greyscale and using a curves adjustment layer. Not much better. I've tried using the black and white conversion dialogue with about the same results. Obviously a clear blue sky is probably a worst case scenario for this problem. I did a search of the forums and people were saying something about converting to 16 bit before you import the image into PS. I got a bit confused and hopefully someone can simplify it for me. I'm not sure how you do this, when I open the image it's in 8 bit. Can you change this in the camera? I use a 50D with sRGB color space. I use Adobe RAW 5.2 and Bridge and I don't see anything about it there.</p>

<p> If anyone would care to share their workflow or has any advice I would greatly appreciate it. I have the feeling I'm just asking to much by pushing the original RAW file to far but hopefully someone knows a way around it. Thanks,<br>

Richard </p>

<p> </p>

[akocurek]

<p>You can change the bit depth in Camera Raw by clicking on the text below the image where it shows your current color space, bit depth, resolution, etc.</p>

[richard_lyman1]

<p> Thanks, that is an improvement. Not perfect but it's giving me a lot more latitude. I take it converting from 8 bit to 16 once already in PS is pointless. Just goes to show you, you can't take everything you read as fact, I was following instructions for b&w conversion in a Photoshop book!</p>

[patricklavoie]

<p>add a layer fill with 50% gray, set the blending mode to softlight, add some noise to it to give it the feel of IR + to reduce / eliminate the banding.</p>

[ellis_vener_photography]

<p>When you do the raw to TIff conversion in ACR don'yt just changethe bit bet bepth from 8 to 16 bit per channel, also changethe color space to Pro Photo.</p>

<p>You might also try doing the color to B&W conversion in ACR and playing with the calibration values as well.</p>

[richard_lyman1]

<p> Thanks everyone for the advice, I was wondering what the Pro Photo space was. I must admit that I'm not really sure of the differences between the color spaces. I have a lot of books but they are huge and I still have a lot to learn. I'll try your ideas. I've gone back and reprocessed some old RAW files in 16 bit and that is a huge improvement! Brought some new life to some I wasn't thrilled with the contrast levels. Thanks again everyone.... Richard</p>

[bill koenig]

<p>Have you tried the infered filter in the B&W ajustment layer in CS4?</p>