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Transcript for Multiple Raw Conversions

for Improved Image Quality -- Part III

Narration by Ron Bigelow

www.ronbigelow.com

Photoshop CS4 Used in this Tutorial

In our last video, we created a mask for the Background Smart Object. While the mask is a good start, it requires some editing before it is acceptable. Let’s start the mask editing by Zooming in to 100% by pressing Contol+Alt+0 on a PC or Command+Option+0 on a Mac.

Using the Navigator, let’s look at the ridges. Actually, the edge between the ridge and the sky doesn’t look too bad. Although, we do need to soften up the mask edges a bit to make a better mask. On the other hand, moving to the region with the trees reveals a problem. Notice the irregularities around the edges of the trees and bushes. Softening the edges of the mask will also fix this problem. So, let’s click the mask and choose Filter/Blur/Gaussian Blur. We are now applying a Gaussian Blur to the mask. The trick is finding the right amount of blur. Too little blur and we do not remove the irregularities that we saw around the bushes and trees. Too much blur and we get halos. I think that a Radius setting of about 3 pixels does a good job.

Now, let’s zoom out by pressing Control+0 on a PC or Command+0 on a Mac.

We need to do some work on the valley. Specifically, we need to darken the valley and remove that harsh transition just below the sky. Let’s go back to our brush tool. We need to change the blend mode back to Normal. In addition, we need to soften up the brush by clicking on the Brush pull down menu and adjusting the Hardness. Then, we need to reduce the Opacity, and check that the foreground color is set to white.

Last, we click on the mask and just paint to edit the mask. That takes care of the Background, but I think that I would like to slightly darken the edge of the farther ridge like this.

There you go. Let’s check out our handiwork. This is what the image looks like without the Background layer. This is what the image looks like with the Background layer.

So, are we done yet? Well, almost. The horizon on this image is slightly tilted (remember the camera was hand held when this shot was taken). If we were going to produce a fine art print, we would need to straighten the image. In addition, I noticed a couple of dust spots that would need to be touched up. However, for this video, we will stop here.

Now, remember in the first video of this series I made you a promise. I told you that we were going to compare a curve edit made in Camera Raw with a curve edit made in Photoshop so that we could see the difference in image quality that results from these two approaches. Let’s do that now. We will not need this image anymore, so let’s close it by pressing Control+W on a PC or Command+W on a Mac.

Let’s open a different image by pressing Control+o on a PC or Command+o on a Mac. Right now, the Camera Raw default settings are being applied to this image. We will not make any adjustments in Camera Raw; instead, we will Click Open Object to bring the image straight into Photoshop without any adjustments.

Let’s open our histogram. Notice how the histogram is very smooth. This is what you would expect to see when there is little or no image degradation. Now, let’s apply a curve to darken the image. We now need to refresh the histogram. Do you see how the histogram became very jagged? This is the way a histogram looks when an image has suffered some image degradation. On the left side of the histogram, the dark tones have been compressed. This causes quantization error. Now, the technical explanation for quantization error is beyond the scope of this video. However, the short explanation is that some of the tones have been lost. So, the pixels have piled up on the tones that are left. Thus, you see spikes in the dark tones where the pixels piled up. On the right side of the histogram, the light tones have been stretched out. As a result, the light toned pixels have been spread over a larger range of tones. This has left gaps in the tones as you can see. All of this results in a degradation of image detail.

Now, to be fair, I must state that this problem is much more significant with eight bit images like this one. With sixteen bit images, the amount of image degradation is less. The degradation is still there; it is just less sever.

Let’s open the file again. This time, let’s apply the curve in Camera Raw. Now, we can move into Photoshop. Look at that histogram. It is very smooth. This is because the curve adjustment in Camera Raw caused little or no image degradation.

So, that brings us back to the whole reason for carrying out multiple raw conversions. Using multiple conversions, when different areas of an image require different editing, produces superior image quality than performing the edits in Photoshop.

Now, I am sure that someone watching this video wants to know why edits in Camera Raw produce a superior image quality than similar edits in Photoshop. Well, that has to do with the differences in working with analogue vs. digital data. On the other hand, that is beyond the scope of this video.

Well, that brings us to the end of this video series. However, before I sign off, I would like to take this opportunity to let you know that you can download the transcripts for this video series, view several other photography videos, and access over 100 photography articles on my ronbigelow.com website.