Optimizing Dynamic Range in Photoshop -- Part III

Article and Photography by Ron Bigelow

www.ronbigelow.com

Photoshop CS3 (Beta) Used in this Tutorial

Fill Light

The Fill Light control is designed to recover detail in the shadows. In addition to the default setting, conversions were done at 33 and 66.

Figures 1 -- 6 show the lower and upper ends of the target at the three settings. Figure 7 shows the summary data.

Figure 1: Lower End of Target for Default Fill Light Settings
Figure 2: Upper End of Target for Default Fill Light Settings
Figure 3: Lower End of Target for Fill Light Setting of 33
Figure 4: Upper End of Target for Fill Light Setting of 33
Figure 5: Lower End of Target for Fill Light Setting of 66
Figure 6: Upper End of Target for Fill Light Setting of 66

Figure 7: Dynamic Range for Fill Light Control
Measured Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
30
9
7.00
33
30
9
7.00
66
28
9
6.33
Eyeball Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
29
8
7.00
33
31
8
7.66
66
27
8
6.33
At first glance, Figure 3 makes it appear that the Fill Light control significantly increased the dynamic range by lightening the shadows. However, the Fill Light control also added a lot of noise. While wedge 34 has a brightness of about 2%, wedges 31 -- 34 failed the noise requirement (with the measured approach). Thus, the lower end of the dynamic range was set at wedge 30. When the setting of 66 was used, the noise problem was even worse. Thus, the dynamic range was decreased.

With the eyeball approach, things are a little better. The setting of 33 did increase the dynamic range somewhat. However, the setting of 66 caused a loss of dynamic range due to noise. Consequently, when using the Fill Light control, the noise in the shadows must be watched.

Full Size Image: Default

Full Size Image: Fill Light 33

Full Size Image: Fill Light 66

Blacks

The Blacks control determines where the black point is set. In addition to the default setting, conversions were done at 0 and 10.

Figures 8 -- 13 show the lower and upper ends of the target at the three settings. Figure 14 shows the summary data.

Figure 8: Lower End of Target for Default Blacks Setting
Figure 9: Upper End of Target for Default Blacks Setting
Figure 10: Lower End of Target for Blacks Setting of 0
Figure 11: Upper End of Target for Blacks Setting of 0
Figure 12: Lower End of Target for Blacks Setting of 10
Figure 13: Upper End of Target for Blacks Setting of 10

Figure 14: Dynamic Range for Blacks Control
Measured Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
30
9
7.00
0
41
9
10.66
10
27
9
6.00
Eyeball Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
29
8
7.00
0
32
8
8.00
10
27
8
6.33
When set at 0, the Black control had a very dramatic effect on the measured dynamic range -- increasing the dynamic range by almost four stops. Furthermore, the recovered tones did better with respect to noise than when the Fill Light control was used.

The tendency might be to start jumping up and down with this exciting news. However, only about one of the recovered stops could be seen with the eye. The other (darker) recovered tones could not be distinguished by the human eye.

Conversely, when set at 10, the dynamic range was decreased.

Full Size Image: Default

Full Size Image: Blacks 0

Full Size Image: Blacks 10

Brightness

The Brightness control is designed to affect the midtones. In addition to the default setting, conversions were done at 0 and 100.

Figures 15 -- 20 show the lower and upper ends of the target at the three settings. Figure 21 shows the summary data.

Figure 15: Lower End of Target for Default Brightness Setting
Figure 16: Upper End of Target for Default Brightness Setting
Figure 17: Lower End of Target for Brightness Setting of 0
Figure 18: Upper End of Target for Brightness Setting of 0
Figure 19: Lower End of Target for Brightness Setting of 100
Figure 20: Upper End of Target for Brightness Setting of 100 
Figure 21: Dynamic Range for Brightness Control
Measured Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
30
9
7.00
0
30
8
7.33
100
31
10
7.00
Eyeball Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
29
8
7.00
0
29
8
7.00
100
30
10
6.66
Since the Brightness control is meant to modify the midtones, one would expect little impact on the dynamic range. This is backed up by Figure 21 which shows that there was only a small change in the dynamic range as the Brightness setting was varied. As such, this control did not have a significant effect on the dynamic range.

Full Size Image: Default

Full Size Image: Brightness 0

Full Size Image: Brightness 100

Contrast

The Contrast control obviously affects the contrast of an image. In addition to the default setting, conversions were done at -25 and 75.

Figures 22 -- 27 show the lower and upper ends of the target at the three settings. Figure 28 shows the summary data.

Figure 22: Lower End of Target for Default Contrast Setting
Figure 23: Upper End of Target for Default Contrast Setting
Figure 24: Lower End of Target for Contrast Setting of -25
Figure 25: Upper End of Target for Contrast Setting of -25
Figure 26: Lower End of Target for Contrast Setting of 75
Figure 27: Upper End of Target for Contrast Setting of 75 
Figure 28: Dynamic Range for Contrast Control
Measured Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
30
9
7.00
-25
31
9
7.33
75
29
9
6.66
Eyeball Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
29
8
7.00
-25
30
8
7.33
75
28
8
6.66
While the contrast control affects all of the tones in an image, it had a much greater impact on the midtones than on either end of the dynamic range. Thus, reducing the contrast setting did increase the dynamic range but only by a small amount. Similarly, increasing the contrast reduced the dynamic range only slightly.

Full Size Image: Default

Full Size Image: Contrast -25

Full Size Image: Contrast +75

Tone Curve

The Tone Curve control determines which curve will be used to lighten and increase the contrast of the raw file during the conversion. In addition to the default setting, conversions were done at linear contrast and strong contrast.

Figures 29 -- 34 show the lower and upper ends of the target at the three settings. Figure 35 shows the summary data.

Figure 29: Lower End of Target for Default Curve Setting
Figure 30: Upper End of Target for Default Curve Setting
Figure 31: Lower End of Target for Linear Curve Setting
Figure 32: Upper End of Target for Linear Curve Setting
Figure 33: Lower End of Target for Strong Curve Setting
Figure 34: Upper End of Target for Strong Curve Setting 
Figure 35: Dynamic Range for Tone Curve Control
Measured Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
30
9
7.00
Linear
31
9
7.33
Strong
29
9
6.66
Eyeball Approach
 
Lower End Wedge
Upper End Wedge
DR in Stops
Default 
29
8
7.00
Linear
30
8
7.33
Strong
28
8
6.66
The Tone Curve had an effect similar to the Contrast control. It had a much greater impact on the midtones than on either end of the dynamic range.

Full Size Image: Default

Full Size Image: Linear

Full Size Image: Strong

Summary of Results So Far

It is a good idea to summarize the results that have been achieved up to this point before moving on to the next step.

Exposure: Decreasing the exposure increased the dynamic range. Basically, very little was lost in the dark tones, but tones were gained in the highlights. Conversely, increasing the exposure decreased the dynamic range due to a very significant loss of detail in the highlights and noise in the shadows.

Recovery: Increasing the setting from 0 (the default) to 33 resulted in a dynamic range increase of one stop. However, increasing the setting to 66 caused no additional gain.

Fill Light: Even though the Fill Light control lightened the shadows so that more of the darker tones could be seen, the lightened tones had a problem with noise.

Blacks: When set at 0, the Black control had a very dramatic effect on the measured dynamic range -- increasing the dynamic range by almost four stops. Furthermore, the recovered tones did better with respect to noise than when the Fill Light control was used. However, only about one of the recovered stops could be seen with the eye. The other (darker) recovered tones could not be distinguished by the human eye. When set at 10, the dynamic range was decreased.

Brightness: The Brightness control did not have a significant effect on the dynamic range.

Contrast: The Contrast control had only a small impact on the dynamic range.

Tone Curve: The Tone Curve had only a small impact on the dynamic range.

Problem with This Analysis

As mentioned in the prior article, there is a problem with this approach to analyzing dynamic range. It only tells what happens when one control is changed while all of the other controls are kept in their default settings. However, the results might be different if the other controls were not in their default settings. This problem will be resolved in Part IV of this series.

Articles

Dynamic Range -- Part II     Dynamic Range -- Part IV