EXERCISE: Managing Tone

You can perform this exercise on any image, ideally one which actually needs some of the adjustments mentioned here (so read through this carefully before choosing the image).  Then use your processing software of choice; the procedures will vary, and you should be conversant with the way in which the software performs the actions listed below.  Depending on whether or not you shoot RAW, there are two procedures, but provided that your camera allows RAW shooting, you should do both.

For this exercise I have used the same image, which was shot in both JPEG and RAW.  Doing this will allow for comparisons between the differences in post-processing allowed within Photoshop for these two kinds of file format.

TIFF or JPEG

In part one of this exercise, I have used a JPEG image; the coursework bullet points suggested the following changes be made to the file:

  • Set the black point and white point.
  • Assess and if necessary adjust the brightness of the mid-tones, your best guide is your own eye.
  • Assess and if necessary adjust the contrast.
  • If necessary, make corrections to localised areas.

Firstly, a copy of the original 8-bit image with no alterations made the data.

Original 8-bit JPEG Image

Original 8-bit JPEG Image

This original image is quiet washed out and the sky lacks contrast or definition.  The histogram confirms that this image is over exposed, as all of the data is squashed to the right of the graph, although there is a good representation of tone, which needs to be given a little more punch and definition within the frame.

Original JPEG Histogram

Original JPEG Histogram

To bring life back to this shot, I have conducted the following keystrokes in Photoshop.

Levels: moved the left slider to the edge of the histogram; doing this made the structure a little darker.

Brightness/Contrast: changed the brightness to -40; this toned down the sky and sea.  Changed the contrast to -15; this softened the edges a little.

Exposure: I then changed the following exposure settings; Exposure -0.35; Offset -0.0018; Gamma 0.95.

As I had made so many changes to this 8-bit JPEG file, the histogram changed quiet considerably and took on the same combing effect I have seen in the past, this is due to the loss of pixels within the image.

Adjusted JPEG Histogram

Adjusted JPEG Histogram

But, I am really pleased with the results received, which can be seen below in the final JPEG image.

Adjusted 8-bit JPEG Image

Adjusted 8-bit JPEG Image

There are two issues with this final image, the first being the banding artefact that can now be seen in the sky and the appearance of dust spots, which were not there when I started processing the file and I was not able to erase once the changes had be made to the layers of the image.

As a comparison, this final image was taken of the same structure, but with the use of a filter, which has produced a very similar image, without the need for any post-processing manipulation.

Same image taken with a Filter

Same image taken with a Filter

You can see that by using the filter I have achieved the same colour balance and tonal range in camera without the need for post-processing tweaks, also, and as I have not needed to play with the JPEG file, there is no banding in the final image, backing up the statement made in the previous post, that if the right choices are made at the time of shooting, no post processing alteration is needed.

RAW

In part two of this exercise, I have used the RAW file of the same image; the coursework bullet points suggested the following changes be made to the file:

There are several good RAW converters available; each has its own way of working and displaying information and tools and you will need to experiment and familiarise yourself with your chose RAW converter.  Also, in the procedures below, we are dealing with just the basic controls.  You will see others, such as Recovery in Photoshop, which have more complex effects.  Use these by all means, but with restraint until you are completely familiar with them.

  • Set the black point and white point by fist adjusting Exposure.
  • Assess and if necessary adjust the brightness of the mid-tones.  There is a choice of methods, including Exposure, Brightness, and Tone Curve.  Experiment with all.
  • Access and if necessary adjust the contrast.  Experiment with both Contrast and Tone Curve.
  • If necessary, make corrections to localised areas.

First, a copy of the original 16-bit image with no alterations made to the data.

Original 16-bit RAW Image

Original 16-bit RAW Image

This image actually appears more washed out than the JPEG file, which confirms that the data is completely uncompressed and gives us more data to play around with.

As this RAW file opened in the RAW converter, I was able to recover the highlights in both the sky and wave tips, I also recovered the blacks back to zero.  Doing this produced the following histogram, which is very similar to the graph for the JPEG image, but is a little smoother around the lighter end of the scale, reconfirming that more data is present in the file.

Original RAW Histogram

Original RAW Histogram

So, having recovered the highlights and blacks, I then moved on to conduct the following post-processing keystrokes:

Levels: moving the slider a fraction on either side of the histogram; as with the JPEG image, this sharpened things just a little.

Curves: playing around with this feature, I created a very subtle s-curve as seen in the following image.

RAW Image Gamma Curve

RAW Image Gamma Curve

Doing this introduced definition in the structure of the pier as well as in the building on top.

Hue/Saturation: by increasing the saturation to +10, the colours in the structures as well as in the sky become more enriched, bringing the image in line with what I saw at the time of shooting the photo.

Making these changes has really made a difference to the Histogram as now the graph has moved away from being over exposed, showing a better dynamic range within the scene, and the overexposed areas contained underneath the pier.

Adjusted RAW image Histogram

Adjusted RAW image Histogram

And here we have the final image, which looks very similar to the JPEG file produced during very similar post-processing alterations.

8.Tone RAW Adjusted

Finally, as before, below is a copy of the image taken using a graduated filter, which has received no post-processing alterations and looks very similar to the image above after its post-processing tweaks.

Same image taken with a filter

Same image taken with a filter

Conclusion:

This have been a valuable exercise as it has not only shown how subtle changes can be made to images using software such as Photoshop, but it has also shown than by getting things right in camera, there is little need for these post-processing alterations to be made.

It is interesting to see how the same alterations can have different effects on different kinds of file formats.  It is possible to make some major changes to JPEG images, but as seen, there is a cost for doing this as image data becomes lost and artefacts can appear within the frame, making things look a little strange and sometimes out of sync.

I am still learning about Photoshop, but the keystrokes used during this exercise are ones I have used in the past, and ones I know I can rely on to bring an image back to life again without making any drastic changes to the image as seen at the time of shooting.

Right now, I could stop learning about image manipulation and just use the skills I have picked up for future processing, but I must admit that I am becoming more and more curious about the software and what it can actually do – I know I have seen others make major changes to their work, but I am looking forward to moving forward and seeing for myself what it is all about!

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