Outer Glow and Drop Shadow Halo / Haze

New Here ,
Apr 02, 2021 Apr 02, 2021

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I am an architect and use Photoshop to digitize my sketches. I have always used Photoshop's effect to punch up the basic line work. However, over the last year, I have noticed a strange haze appearing. It is extremely noticeable with Outer Glow, but still occurs with Drop Shadow. Recently, I have switched to Drop Shadow to avoid the issue blatantly occurring with Outer Glow. But, I don't think it is an error. I think it is a matter of understanding the mathematics behind Opacity, Spread, and Range.


In "2.jpg," an Outer Glow is applied. Its Opacity is 100%, its spread is 0%, and its range is 50%. In my mind, this indicates the linear contour will immediately fade from 100% to 0% over the Size of the Outer Glow. In this instance, the Size is 50 pixels.


In "1.jpg," the problem occurs. At times, I not only want a glow to my line work, but I want to punch them up by increasing the Spread. I increase the Spread to 20%, but lower the overall Opacity to 80% to avoid making the line work blurry.  In my mind, this indicates the linear contour should fade from 80% ( the Opacity ) to 0% after an even Spread of 20% the Size of the Outer Glow. However, the Spread is not even. There is a darker ridge and a strange halo created before the linear contour takes control of the fade to 0%. Why?


Yesterday, I felt Spread and Range may be inversely related. Bumping Range up to 70% appears to counter a Spread of 20%. But, what happens if the Spread is greater than 50%? You can't increase Range above 100%. So mathematically, this is likely not the case. Plus, none of this solves the strange transparency of the Outer Glow before the Linear Contour takes control at 20% Spread.


I briefly thought the issue may be the Contour. Perhaps, the Contour "always" changes from 100% to 0% based on its shape. What if I program the upper end of the Contour to be set to 80% "Opacity," so the darker ridge is eliminated. However, this doesn't make sense because setting the Outer Glow's Opacity at 20% doesn't result in a darker ridge of 100%. Again, mathematically this doesn't compute. However still, some of the other Contours do mitigate the effects of this issue, but unfortunately, none fully solve it.


I have submitted this same question to Phlearn and spent approximately three hours sharing screens with Adobe, but no one has been able to explain the true relationship between Opacity, Range, Spread, and Contour. Any help would be greatly appreciated.


Oh! I almost forgot. "Drop Shadow.jpg" depicts a real example, but in this instance, I am using Drop Shadow and the resulting haze is circled. And, "Range Graphic.jpg" depicts my understanding of Range.

Bug, Problem or error








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