stephen_jennings Posted February 25, 2015 Share Posted February 25, 2015 <p>I've been experimenting with using ProPhoto as my working space in Photoshop, but I've been having problems with posterization that I don't understand. I have a wide gamut monitor that is well calibrated and profiled; I shoot RAW, output a 16-bit tiff in ProPhoto, open it in Photoshop with the ProPhoto working space set. Several times I've tried to lighten an area in the image by making a selection, creating a layer and setting the blend mode to Screen, but I get posterization in light/dark transition areas and banding in smooth areas. I thought that using 16bit files prevented this from happening, but it seems not. Is there a way around this, or am I better off sticking with AdobeRGB?</p> Link to comment Share on other sites More sharing options...
digitaldog Posted February 25, 2015 Share Posted February 25, 2015 <p>The banding is probably on-screen and not in the data. There will be no banding in ProPhoto RGB from editing the data in high bit. It may preview as such, that's an issue with the display path. <br> You might want to upload a layered doc (not too big) for us to examine. </p> Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com) Link to comment Share on other sites More sharing options...
Tim_Lookingbill Posted February 25, 2015 Share Posted February 25, 2015 <p>What zoom level are you viewing this? Does the banding show up in 100%? 25? 33.33%?</p> Link to comment Share on other sites More sharing options...
steven_clark Posted February 25, 2015 Share Posted February 25, 2015 Also as a dumb question that needs to be asked: Are you using soft proofing? I've heard sometimes output profiles skimp on the Look Up Tables going back to the connection color space and the result can be posterization when soft proofing. Link to comment Share on other sites More sharing options...
digitaldog Posted February 25, 2015 Share Posted February 25, 2015 <blockquote> <p>I've heard sometimes output profiles skimp on the Look Up Tables going back to the connection color space and the result can be posterization when soft proofing.</p> </blockquote> <p>They shouldn't. And these profiles have two tables. One affects the output, the other the soft proof. So again, if what you say is true, it's a display issue, not an issue with the output data. </p> Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com) Link to comment Share on other sites More sharing options...
digitaldog Posted February 25, 2015 Share Posted February 25, 2015 <p>Stephen, do you see any differences if you view the ProPhoto data after conversion to 8-bits per color? </p> Author “Color Management for Photographers" & "Photoshop CC Color Management" (pluralsight.com) Link to comment Share on other sites More sharing options...
Ed_Ingold Posted February 25, 2015 Share Posted February 25, 2015 <p>One way to detect posterization in an image file is to examine its histogram in Photoshop. Posterization is often accompanied by gaps in the histogram, although most often in an 8-bit rendering of the image.</p> <p>Andrew's suspicion of the monitor and viewing stream is worth consideration. I have experienced this with a cheaper Viewsonic monitor, mainly in bright, smooth toned areas like the sky in a sunset photo. It's reminiscent of a "paint by numbers" craft set. I have not seen this effect with my current NEC monitor and fairly high-end 32 bit video card. Nor did I see posterization when printing these same images on an Epxon 2200 from Photoshop.</p> <p>There are ways and ways to profile and calibrate a monitor. In the end, calibration uses a lookup table to tweak data sent to the video card. In a proper calibration, you should adjust the manual controls on the monitor to achieve a 90% solution before proceeding with the calibration. It will work anyway, but the profile squeezes the image into only a portion of the monitor's gamut to achieve all of the corrections.</p> Link to comment Share on other sites More sharing options...
stephen_jennings Posted February 26, 2015 Author Share Posted February 26, 2015 <p>I did try converting the posterized image to AdobeRGB, but not 8bit, and the posterization remained. I'll try changing the bit depth as well and see.<br> As for soft proofing, I generally leave it on, and play with Rendering Intents.</p> Link to comment Share on other sites More sharing options...
dag_fosse Posted February 26, 2015 Share Posted February 26, 2015 <p>While masks have the same bit depth as the document, selections are always 8 bit. So if you are basing your adjustments on selections, you'll very likely see banding. Especially in the shadows, where ProPhoto is very compressed compared to ARGB or sRGB.</p> Link to comment Share on other sites More sharing options...
Tim_Lookingbill Posted February 26, 2015 Share Posted February 26, 2015 <blockquote> <p>Several times I've tried to lighten an area in the image by making a selection, creating a layer and setting the blend mode to Screen, but I get posterization in light/dark transition areas and banding in smooth areas.</p> </blockquote> <blockquote> <p>As for soft proofing, I generally leave it on, and play with Rendering Intents.</p> </blockquote> <p>So you're Soft Proofing and using Screen blend modes at the same time? Does the posterization go away when you toggle the Screen blend mode off/on?</p> Link to comment Share on other sites More sharing options...
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