Reflections on the exercise "Tolerance for noise"

This exercise looked at digital noise, the situations when noticeable noise appears, the way it manifests in images and how to manage the negative effect it might have on the quality of images.  

Following the instructions given in the Exercise 3, I made a sequence of ten images, changing ISO setting so that each image is one ISO setting apart from the previous.

All images were shot at f/8, 100mm.

Image1

The image was exposed for ½ second at f/8, ISO setting 50.

This is the ISO setting that I usually use and I am very comfortable with the quality that this setting delivers. There is no visible noise even at higher magnification. 

My default position is not to go higher if at all possible.

Quote for the day: Ernst Haas

The camera does not make a bit of difference. All of them can record what you are seeing. But you have to SEE.                                      Ernst Haas, Comment in Workshop, 1985

Highlight clipping: lessons

My lessons learnt from this exercise:

1. The three RGB channels do not clip the highlights and shadows in the same way and it’s usually possible to recover some detail in highlights and shadows using the Recovery and Fill Light / Blacks tools.

2. Although highlight and shadow clipping usually represents a problem, it’s also possible to use it creatively to achieve special and unusual effects.

Highlight clipping: using the recovery tool

Using the Recovery Tool

When applying the Recovery tool to the overexposed images, I discovered that it’s possible to achieve a reasonable quality and realistic looking result where overexposure is around 1 f-stop. If the overexposure is greater, the‘re-built’ areas of highlights displays some unrealistic colour cast, with most affected areas turning completely grey.

I also tried the Recovery tool in the Threshold mode (Adobe Lightroom) and found it quite useful.

My key tools used to manage the highlights and shadow clipping remain the following: highlight clipping warning in my camera setting (I usually have it on) and Recovery/ Fill Light/ Blacks tools in Adobe Photoshop and Lightroom.

My final image for this exercise showing the best compromise position of highlight and shadow clipping is below.

More on highlights: my learning from the exercise 2 on 'highlight clipping'

Image 5

This image was exposed for 1/60s at f/11.

The highlight clipping is appearing across a much wider area of the sky. 

Analysis of the magnified image shows that:

There are some areas that display a complete loss of visual detail.

It’s possible to see a clear break in the edge between nearly-white and total white.

A colour cast is noticeable in the areas around the clipped white highlight, particularly slightly below the area displayed in the magnifications.

The colour saturation is affected mostly in the areas immediately adjacent to the affected parts of the image.

Images 6 and 7

Image 6 was exposed for 1/30s and image 7 for 1/15s at f/11.

The highlight clipping is progressively taking over the whole are of the sky and is spreading down to the river. All reflective areas (such as the river and shiny metal details of the bridge) are affected.

Image 7 displays a complete loss of highlight detail. The colour saturation of the whole image is affected with all the colours, even those in shadow areas, appearing dull. There is a really unpleasant colour cast appearing in the areas bordering with the clipped highlights. There is a clear and visible break between nearly-white and total white.

A quote for the day: Ansel Adams

When words become unclear, I shall focus with photographs.  When images become inadequate, I shall be content with silence. 
                                                                                                                    Ansel Adams

A quote for the day: Ansel Adams

A photograph is usually looked at - seldom looked into. 
                                                                                               Ansel Adams

Highlights and shadows of my learning from the exercise 2 on 'highlight clipping'

This exercise looked at highlight clipping and how a digital camera records highlights and overexposed parts of an image.

Following the instructions given in the Exercise 2, I made a sequence of seven images, each separated by one f-stop. Five images were required for this exercise but I decided to extend the sequence to seven to observe the impact of both highlights and shadow clipping at the extreme ends of under- and overexposure. 

All images were shot at f/11, ISO 50, 24mm.

Image 1.

The image was exposed for 1/125s at f/11.

The highlight clipping just began to occur in the isolated spots and at this exposure only the whites of the clouds are affected.

Analysis of the magnified image shows that very little loss of visual information has occurred at this stage.

A break between nearly-white and total white is almost unnoticeable. There is no obvious colour cast and the colour saturation does not seem to be affected.

Image 2

This image was exposed for 1/250s at f/11. The highlight clipping is not present. Instead there are areas of shadow clipping occurring in the most underexposed parts of the image. The whites of the clouds are perfectly exposed.

Analysis of the magnified image shows that some loss of detail (visual information) occurred in the shadow areas. There is noticeable colour cast along a fringe bordering the clipped shadow.

The colour saturation of the highlights bordering the clipped areas of the image is affected slightly, although this might be more to do with the sun playing on the shiny metal surfaces.  

Images 3 and 4

Image 3 was exposed for 1/500s at f/11 and image 4 was exposed for 1/1000 at f/11.

The highlight clipping is not present and the areas of shadow clipping are progressively dominating the scene. There are wide areas showing complete loss of visual information, where it’s hard to distinguish any detail.

There is more pronounced colour cast along the border of the clipped areas and the colour saturation of the whole image is increasingly affected, including the highlights. The colours are no longer represented correctly across all areas of the image. 

In the shadow areas, a loss of visual information is beginning to appear. 

Highlight clipping: dealing with non-reflective highlights

I am reading Martin Evening's Adobe Photoshop Lightroom Book and I've just found some interesting details about treating non-reflective highlights.
Non-specular or non-reflective highlights need to be treated differently from the specualtive. This is because they contain important details that need to be preserved.
I usually use the clipping gamut warning to judge if the highlights clipping has occured. Martin also recommend adjusting Recovery slider in Threshold mode.
I've never used the Threshold mode before - I am going to try that and see if it works for me.

Highlight clipping: when to clip highlights

I am working on the Exercise 2 (Highlight clipping) of my 2nd assignment and have just been looking through Martin Evening's Adobe Photoshop for Photographers. I came across some interesting detail in Chapter 3 related to the topic:
1. Is it always necessary to save highlights or are there situations when it is safe to blow them out to white? Martin uses the term 'specular highlights' to describe highlight reflections found on shiny metal or similar surfaces. He makes the point that because these highlights contain no detail, it is safe to clip them so the highlight point could be set to a higher level [p.170. Martin Evening, Adobe Photoshop for Photographers, 2009]. Trying to preserve detail in specular highlights will limit the contrast of the whole image so other areas might look too dull. Using recovery adjustment might help to optimase the image with high contrast. 
2. When adjusting the Exposure and Recovery sliders it is important to consider whether highlight details are matter or not. With the highlights, CMYK printers may be unable to produce a dot that is light enough to print successfully [p.168. Martin Evening, Adobe Photoshop for Photographers, 2009].