Graduated Filter Question

[JAY-DEE PURDIE]

Lightroom Version Number

10.1

Operating System

1. macOS 11 Big Sur

Hi … I’ve been using Lightroom regularly and I often make use of the graduated filter with success. I‘m not sure where my mind went today but it occurred to me that I didn’t have a clear and definitive definition for the meaning of the three lines … upper, middle and bottom. I did a search on numerous web sites, including Adobe, but nowhere could I find this info. I located tons and tones of YouTube and help sites with examples of how to use the graduated filter, but nothing defining the three lines.

Does anyone have a source for this info or know the answer.

Thanks from a very curious amateur photographer … Jay-Dee

 

[johnrellis]

Intuitively, if you're drawing the graduated filter from the top down, then the top line applies the filter's settings at full strength, the bottom line applies it at zero strength, and the middle line represents partial strength.

I was curious about what that means quantitatively, so I nerded out with an experiment. I applied a graduated filter to an all-white image, left to right, spanning the entire width of the image, with Exposure = -4. As expected, this results in a smooth gradient from grey (with Exposure = -4) to white (Exposure = 0):

Using Photoshop to sample the pixel colors, I made a plot of the pixel values going left to right, with 100% = white and 0% = black:

As expected, the S-shaped curve provides a smooth horizontal transition. If it were a straight line, then your eye could perceive the start and end of the filter as sharp edges.

Interestingly, at the middle of the filter (50%), the pixel value of 75% is more than halfway between the darkest (28%) and lightest (100%) pixel values of the filter (halfway is 64%).

 

[Rob_Cullen]

A good "nerdy' answer with explanation. Thanks John!
I had always believed-
First line = 100% of the Slider Settings. (No sliders adjusted = no effect)
Middle line = 50%
Last line = 0%
The most interesting 'trick' IMO, with the Gradient is to draw it outside the image and drag away from the image, which applies a 100% (slider settings) effect to the whole image. (Very useful with the Range Mask settings)

 

[Paul McFarlane]

You could also just look at page 270 of your Classic FAQ book (2nd Edition) that confirms that.

 

[JAY-DEE PURDIE]

John … thanks for your reply. I love answers like yours that not only tell me what I want to know, but also the detailed proof. Your response helped a lot And I really appreciate that you made time to experiment the way you did. Thanks.

Also thanks to “I-See_Light” and Paul for responding.

Paul … thanks … I did read page 270, item #4, before I posted my question, and I wasn’t quite certain in that it just referred to the outer line and no reference is made to the other two lines. Intuitively, I assumed when creating the graduated filter from top to bottom, then the outer line would be the top line. But there was no reference to the middle and bottom line on page 270. John’s answer was very thorough in not only what the lines were for but also the detailed impact of the lines.

Thanks all … Jay-Dee

 

[Paul McFarlane]

Paul … thanks … I did read page 270, item #4, before I posted my question, and I wasn’t quite certain in that it just referred to the outer line and no reference is made to the other two lines. Intuitively, I assumed when creating the graduated filter from top to bottom, then the outer line would be the top line. But there was no reference to the middle and bottom line on page 270. John’s answer was very thorough in not only what the lines were for but also the detailed impact of the lines.

Thanks, good feedback, we'll see if we can make it clearer!