Saturday, 16 October 2010

PP Tips 1- Preserving Highlights

This is the first part of a 'How To' series on post process work.

This first one deals with a technique to preserve highlight areas, whilst doing any post process work in Photoshop.

Note : The text in the image examples may not appear as clearly on the blog as I would like, so please follow the written text also.

Firstly, the objective of the edit for this first example image is quite simple - I wish to sharpen it and also lighten it very slightly. Doing either will have an affect on the highlight areas, so the aim is to preserve those areas while I do other adjustments.

The image was shot in Jpeg, however, whether I shoot Jpeg or Raw, I open all my images in Adobe Camera Raw (ACR). This allows me to quickly see if the image has any areas which are 'clipping' highlights or 'blocking' shadows.

I have chosen this image as an example, as it is shot in a very high contrast situation. This was shot about one hour after sunrise, and I am (almost) facing into the sun. At the bottom of the page, is a second example which was shot at the same time, but with the sun behind me.

You can see in this first image, that there is very slight highlight clipping (bright red), and also a very small amount of shadow blocking (bright blue in the dark areas).

Note : In the commentary, I will simply use the term 'clipping' to refer to either.

Normally, I do many of my adjustments in ACR but, for the purposes of this exercise, I will simply open the image and do any adjustments in Photoshop.

The image as opened in ACR.

Step 1

With the image open in Photoshop, the first step is to go to Select/Color Range and select that option.

Step 2
Once the dialogue box opens, check the Invert box and then select Highlights. What this is doing is to select an area around the highlights, but inverting that selection so the highlight area is not selected.

Step 3
It is important to 'feather' the area around our selection, so that any adjustments blend into our non-selected area smoothly.

Note : For this image, I selected a feather value of 15. I normally work somewhere within a range between 15 and 45. It is fairly much image dependent. If you wish to have a 'one-fits-all' selection, then 22 works in most situations 

Step 4
Once our area is selected, the next step is to make any adjustments.

Here, I am using Levels (Image/Adjustments/Levels) to 'push' the darker areas up, whilst preserving some of my overall contrast, and to also set values to help limit the amount of any clipping.

Values used here are : Input Levels - 0, 1.05, 220 and Output Levels - 4, 250

Step 5
For levels adjustments, that is all I am going to do. However, I am now going to run my own sharpening action, which also does a couple of 'tricks' which affect local contrast.

Note : If you would like this action, you can download it from the link below. It's free, gratis, no strings attached. 

The action is here - Sharpening Action

The image below now shows the original image (left) and the adjusted image.

Below is the original image and then following that is the adjusted image.

This second example was shot at the same time as the first, but with the sun behind me.

The original image.

The adjusted image.

The same highlight preservation technique was used as in the first example. The simple objective here was to apply sharpening and also to give the image an appearance of greater contrast.


Other posts in this series - Click here for the index page.


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