There are tons of bits and pieces of info out on the web that describe the proper use of vibration reduction technology (VR). Thom Hogan recently posted the most detailed and comprehensive discussion of this important subject to date – a must read! Find the entry, entitled ‘All About VR’, here.
Archive for the ‘Methods’ Category
Apr
27
2010
Cisco, UT 84515
Cisco, Utah, was born during the late 19th century era of the steam engine, and became an important watering stop for the locomotives. The railroad station became a key shipping center for the livestock that were managed in the open range country of the Book Cliffs. Unfortunately, the diesel locomotive made stops at Cisco unnecessary, and by the 1950′s the long decline of the town had began. Unlike Greenriver, which lies adjacent to I70, and which is an important stop for travelers, Cisco was left too far off of the freeway to gain significant commercial traffic. Hard luck.
The image above, of the old Cisco post office, was recorded on April 18, 2010 at about 12:40 MDT, using the Nikon D3s and the (new) AF-S NIKKOR 16-35mm f/4G ED VR lens at 16mm. Exposure was f/16 and 1/160s, ISO 400. One RAW images was converted to HDR using Photomatix 3.1 ( see below for for processing details).
Regional guides list Cisco as a ghost town. I’m not so sure, since while it certainly does have certain attributes of a ghost town, it has also been exploited as a junk yard – plenty of character to be sure, but for ghost town aficionados it’s most probably not the real deal. Regardless of how you define it, the place certainly is a great location at which to refine your High Dynamic Range photography (HDR) skills. Light, dark, decrepit structures, old, abandoned cars, it’s all in there. The circumstance lends itself most naturally to what I will name – without any judgment – fantasy HDR. For you HDR aficionados, by ‘fantasy’, I mean to conjure up the effect one gets with (in Photomatix language) Detail Enhancer mode tone mapping conversion. Of course we’ve all seen this effect, and there is tons of this stuff on the web – some of it is very nice. I include links to a few of the more active HDR sites that describe Detail Enhancer mode strategies below:
http://www.aguntherphotography.com/tutorials/raw-hdr-processing.html
http://www.stuckincustoms.com/
http://www.vanilladays.com/gallery/tag/hdr/
http://www.robertcorrell.com/
The full Detail Enhancer mode specifications for this file are shown below:
Photomatix Version 3.1
Method: Details Enhancer
Luminosity: 5
Strength: 100
ColorSaturation: 88
WhiteClip: 5.0
BlackClip: 5.0
Smoothing: High
Microcontrast: 10
Microsmoothing: 2
Gamma: 1.0
HighlightsSmoothing: 0
ShadowsSmoothing: 0
ShadowsClipping: 0
ColorTemperature: 0
SaturationHighlights: 0
SaturationShadows: 0
Copyright 2010 Peter F. Flynn. No usage permitted without prior written consent. All rights reserved.
Feb
27
2010
The Myth of the Golden Hour, Part IV
The image above was recorded in The Wave at about 12:20 MST on August 27, 2009, using the Nikon D700 and the AF-S NIKKOR 24-70mm f/2.8G ED lens at 45mm. Exposure was f/16 at 1/250s, with an ISO of 200. The Wave is found in the Coyote Buttes North section of Vermilion Cliffs National Monument in Utah/Arizona.
In a previous installment in this series I’ve indicated that the contribution to image contrast of the individual red, green, and blue channels are unequal. In fact, the green channel contributes twice as much as the red channel, and the red channel contributes three times as much as the blue channel. There are quite natural reasons for this curious channel weighting, which we will consider in a future entry. For the current consideration we will focus on how we can modify the apparent weighting of the contributions of the individual R, G, and B channels.
The book says that an image recorded at midday is likely to be weak, e.g., lacking color saturation and contrast. Admittedly, perhaps the composition is a bit ordinary, but there is nothing lacking in the image above in terms of image contrast and color saturation. On the other hand, and as is shown below, that is not how this image started out.
Well, this is obviously an overexposed image you might say. Nope, check the histogram.
I bracketed this shot too, and this is the best compromise between overexposed and muddy. The lack of contrast is a result of shooting the scene with the sun pretty much exactly overhead – what audacity!
We appear to have quite a way to go to bring the source image to the final image, but it’s actually quite straightforward. Begin by reviewing the red, green and blue channels of the source image. First copy the Background layer, (cntl>j (<cmd>j on the Mac) to generate a new layer (Layer 1). Then select the red, green, and blue channel panels in turn in the CHANNELS palette.
As you can clearly see below, the green channel possesses much better contrast than the red channel – this channel is in pretty good shape.
The blue channel (below) has much better contrast than the red channel.
To enhance contrast in that weak red channel we simply replace the red channel (blend) with the blue channel. To accomplish this replacement, we employ the Apply Image tool to execute the blend by first selecting the red channel, and then typing Image > Apply Image, and then specifying that the blue channel be added to the red channel in Normal blending mode at 100% opacity. The result is shown below.
While you might be able to appreciate the contrast enhancement, the resulting influence on color dominates your impression. We can restrict the influence of channel blending by changing the blending mode of the Background copy layer to Luminosity. The result of the change in blending mode is shown below, with the original source image shown below that image for comparison.
This is a significant improvement. The contrast is then further enhanced by applying a curves adjustment to the red and green channels (you could also apply a curve to the blue channel, the influence on the overall image contrast would be small).
To finish processing of the image we apply the image to itself in Multiply blending mode by first flattening the image, and then copying the resulting layer and changing the blending mode to Multiply.
Finally, we apply Shadow/Highlight adjustment to open up the mid tone range a bit: select Image > Adjustments > Shadow/Highlights…
I hope that you’ve found this entry useful. If so, please drop me a line and let me know what you’d like to see in future posts. Cheers, P.
Copyright 2010 Peter F. Flynn. No usage permitted without prior written consent. All rights reserved.
Feb
17
2010
A Moment in Time Recovered
Whether it’s a box of photos, or pages in an album, to a keen archivist it’s the challenge of the undiscovered country, a set of visions created by dear friends or relatives, to be rendered in modern digital terms.
The image above represents three generations. On the left is Meredith, her mother Helen in the middle, and her mother-in-law, Margaret, on the right. Standing behind her mother and grandmothers is the HP as a young lady. This is just an awesome composition, but what attracts me most to this image is the HP’s classic Mona Lisa smile, and those eyes.
My father in law, Carl J. (Joe), was an inspired shooter, who has left his family with a great wealth of images. Joe shot using a number of formats, including Kodak 126 format and and 35mm, with output rendered at the local photo mill standards of the time. The image above was recorded using a Praktica 35mm camera. The source image for the restoration, shown below, was a scan of the printed image generated using an HP ScanJet at 1200 dpi – yes, there are better scanners, but honestly, I’m not certain that they help much.
The image was scanned into RGB colorspace. Contrast was enhanced by adding a curves adjustment to the individual red and green channels. The image was then converted to BW, and the contrast then further enhanced using Nik Silver Efex Pro. Noise and dust were removed a combination of the Clone Stamp and Healing Brush tools in Photoshop CS4. In practice I find that regions that have a constant tone are most efficiently repaired using the Clone Stamp tool, whereas the Healing Brush tool generally works better on regions that contain complex patterns. In all cases, keeping the brush size as small as possible generally produces the most favorable results.
The heavy lifting in this image was the removal of an outdoor service outlet along the wall just above and to the right of the head of little HP. I cloned in a replacement seam from the set of shakes that lies to the right of where that service outlet exists using the Clone Stamp tool. Reasonably convincing if I do say so myself.
If you are serious about image recovery, there are a number of excellent published texts on the subject. My current working texts are Scott Kelby’s ‘The Adobe Photoshop CS4 Book for Digital Photographers’, Katrin Eismann’s (with Wayne Palmer) ‘Photoshop Restoration and Retouching’, and Ctein’s ‘Digital Restoration from Start to Finish, Second Edition: How to repair old and damaged photographs’.
Copyright 2010 Peter F. Flynn. No usage permitted without prior written consent. All rights reserved.
Feb
04
2010
The Myth of the Golden Hour, Part III
In Part II in the series we discussed an overlay method that improves definition in the highlight areas of the image. Part II was published on January 22, and Part I was published on January 13. In this installment, we will consider a method for enhancing contrast by application of a curves adjustment layer. Our working image is shown below.
Currently, we have three layers: the top layer is a copy of the original unprocessed copy of the image in darken mode, a middle layer overlay layer, and the original image on the bottom. Let’s flatten the layer by opening the Layers submenu (click the downward point arrow in the upper right hand corner of the Layers tab) and selecting the Flatten option.
Then copy the resulting Background layer to generate a new Background copy layer.
A curious condition of RGB images is that the contribution of the red, green, and blue channels to the luminosity (contrast) present is not equal. We will leave a technical discussion for why this is so for a future entry, but in fact the green channel is most important, followed the red channel and then the blue channel in the ratio 6:3:1. This suggests that we could delete the blue channel and retain 90% of the current image contrast – it’s true!
To review the contribution of the individual channels we open the Channels menu, select Window on the Photoshop top menu bar, and then select the Channels item from the drop down menu.
By selecting the individual Red, Green, and Blue channels in the CHANNELS tab in turn, we can see what each of these elements brings to the overall image – note that when a channel is selected, the channel indicator turns blue ( assuming default Photoshop behavior).
Select the red channel panel to activate only that channel.
Select the green channel panel to activate the green channel only.
Finally, select the blue channel panel to activate the blue channel.
Careful review of the individual channels confirms that they are all about equal in terms of providing elements of contrast to the image. This will not always be the case, especially in images recorded in red rock country. In this case, the most straightforward approach to improving contrast will be to apply curves adjustment to the individual red and green channels (the blue channel may be adjusted, but in practical terms, such adjustments have minimal impact).
Begin by conducting a merge-copy by typing <cntl><shft>alt>e (<cmd><shft>alt>e on the Mac) This merges the current three layers into one layer, and then copies that layer on top of the others. We could have simply flatten the three layers and then copied the result, however the merge-copy gives us a bit of additional flexibility, e.g., we could always delete the merge-copy layer and then rework the darken or overlay layers.
So that we can remember how all the current layers were generated, let’s rename them by selecting (double-click) the text in the LAYERS tab.
We now load the red channel by selecting that channel in the CHANNELS tab, and then apply a curve to the channel by typing <cntl>m (<cmd>m on the Mac).
Notice that I have steepened the curve near the maximum on the right hand side of the histogram (note that I have rendered the histogram so that it displays the amount of light – this is the default setting, however I usually rig it to show % pigment/ink). The right side of the histogram is where the luminosity of the lighter rock surfaces is represented, and steepening the curve in this region increases contrast in the rocks.
We apply a curves adjustment to the green channel to further enhance the contrast in the rocks.
Since we are working in RGB color space, luminosity and color are intrinsically tied together. Thus the curves we have applied to the red and green channels generate not only a change in luminosity (contrast in the BW sense), but also a color shift. We can fix this easily by simply changing the blending mode of the Merged-copy Layer to luminosity to produce the contrast-enhanced (only) image shown below.
Compare this image (above) to the one we started with in this entry (below).
Next, we merge-copy to generate a new layer on top, and change the blending mode of the new layer to multiply.
Finally we adjust the opacity to until things agree with our vision of the place, about 60%, to finish up this lesson.
This was a long discussion, perhaps too long for most. Anyway, I hope you find it useful. Send questions if you got ‘em. There is a quote by Edward Weston that I favor: “Photography to the amateur is recreation, to the professional it is work, and hard work too, no matter how pleasurable it may be”.
Copyright 2010 Peter F. Flynn. No usage permitted without prior written consent. All rights reserved.
Jan
22
2010
The Myth of Golden Hour, Part II
The image we will consider in this entry is the often-photographed Horseshoe Bend site near Page, AZ. The overlook is located about 6 miles south of Page on US 89, at the end of a 0.75 mile hike (one-way) over rolling sandy terrain. The final processed image is shown below.
The source image (shown below) was was recorded on July 22, 2009, at about 14:40 MST, using the Nikon D700 and the AF-S NIKKOR 24-70mm f/2.8G ED lens at 27mm. Exposure was f/16 and 1/125s, ISO 200. Minimal processing of the RAW image was conducted during the conversion.
The image exhibits the anticipated washed-out attributes that we would anticipate given the time of day at which the image was recorded. In this instance, as we so often find, photographing this amazing scene during the Golden Hour is simply not tractable, since long shadows would fill the canyon, generating an uninteresting image. Our only option is to record the image when the sun is relatively close to its zenith, and hope to enhance detail and color post-capture.
Below, I include a screen capture of the ACR Raw conversion interface below to illustrate that although the image it pretty washed out, the histogram indicates that things aren’t too bad – this is common is images recorded near midday on sunny days.
There are several things would should like to improve. The clouds on the horizon are attractive, but a bit blown out. There is dramatic color variation, but it definitely could be much better. Specifically, both contrast (luminosity) and color variation would be improved by both darkening the sandstone surfaces throughout the image and by expanding the subtle range of color present.
We’ll tackle the clouds/sky issue first. We begin by copying the Background layer to generate the Background copy layer.
The next move is difficult to motivate, but the results are compelling. Apply the blue channel of the RGB image to the R,G, and B channels in Normal blending mode – select Image > Apply Image… Note that the Invert box is checked – this is important. See the dialog box and resulting image below.
Not yet clear where this is headed? Try changing the blending mode of the Background copy layer from Normal to Overlay blending mode as shown below.
Although you may be able to see that we have increased definition in the clouds, the image still looks pretty strange., and specifically there is an odd loss of resolution throughout most of the image We clear this up by blurring the Background copy Layer. Make certain that the Background copy layer is selected (the layer icon will turn blue if you are using default settings). Then select Filter > Blur > Gaussian Blur… The Gaussian Blur dialog box will appear, and allow you to vary the radius parameter.
The proper setting of radius depends on the resolution of the image. As you increase radius, the image will gain back the original resolution of the source image, but the clouds – and – other highlight regions of the image – will have improved definition. For this 12MP image, I had to apply the maximum value, 250 pixels, twice. The Photoshop engineers definitely need to increased the range of the radius parameter to accommodate current and future image sizes. The resulting image is shown below.
Careful comparison between the working image shown above and the original image indicates that the Overlay procedure has left the image much lighter. We restore the original luminosity by first copying the Background image to generate a new layer named Background copy 2, and then draging that new layer to the top of the layers stack as shown below.
Of course, since the blending mode of the new layer is Normal, the view you now have of the image is exactly the same as when you started – placing any image with blending mode set to Normal at the top of a layer stack simply displays that image. Things get interesting when you convert the blending mode to Darken as shown below.
The influence of the processing becomes clear when we view a section of the sky as shown below – original image on the upper half.
Note that not only has the definition in the clouds improved, but the canyon walls have also been enhanced. This is a good stopping point for the current entry. Stay tuned for part III.
One final note. I didn’t invent any of the methods discussed in this entry. My approach is a combination of a wide range of influences, including ideas discussed by Martin Evening, Bruce Fraser, Scott Kelby, Dan Margulis, Deke McClelland, Jeff Schewe, Rov Sheppard, and a number of others – all of the folks listed by name publish excellent texts on image processing and are well worth owning.
An image of the Horseshoe Bend area is shown below courtesy of Google Earth Imaging.
Copyright 2010 Peter F. Flynn. No usage permitted without prior written consent. All rights reserved.
Jan
15
2010
Save Your Edits!
A key element of processing images for contrast enhancement and color correction and enhancement is tracking what works well. To accomplish this, you will need to record all the adjustments you make on your more challenging/succesful projects. Fortunately, Photoshop will easily sort all of this out for you. After experimenting with a number of variations, I suggest the following. Begin by opening the General Preferences dialog box by selecting File > Preferences > General:
Activate history logging by selecting the History Log check box. Next direct the log to the file metadata by selecting the Metadata radio button. Finally, select Detailed from the Edit Log Terms pull-down menu to record a complete record of the adjustments.
To review the your adjustments, select File > File Info…, and advance the tab to the History panel. The History panel will provide a sequential list of literally every adjustment made to the processed image. It may take you a little while to get the hang of interpreting the history dialog, but soon you sort it all out.
Any adjustments made in the image processing are now automatically saved in the image file. Just a little effort in reviewing why things seemed to look better goes a very long way. At any rate, feel free to check for more practical hints on converting your captures into excellent final processed products.
Jan
13
2010
The Myth of Golden Hour, Part I
The Golden Hour is a classic photographic nutshell that recommends that the best times for recording images are approximately the first hour after sunrise, and the first hour prior to sunset. This concept is so neatly set in the minds of photographers that it has come to suggest that high quality images can only be recorded during the Golden Hour intervals. The point of this series of entries is not so much to debunk the idea, as to provide a practical example of the relatively facile and powerful modern digital processing methods.
We should first consider what it is about the Golden Hour that make this time so special for recording photographic images. During the Golden Hour, the angle of the sun with respect to the horizon is small, certainly less than 15°, so that the light directly from the sun travels a greater distance though the atmosphere; which reduces its intensity, and also produces characteristically relatively long shadows. Moreover, the relative contribution to the overall light intensity from the sky is enhanced. This sky light is characteristically extremely diffuse, e.g., think of the sky as the ultimate light diffuser. In terms of the color of the light, the longer path traveled by the light leads to a relative decrease in the blue component due to dispersion, leaving a relative enrichment in yellow and red components.
On the day that the image shown above was recorded, August 28, 2009, sunrise occurred at approximately 06:50 MST. The image was recorded at 10:45 MST, well outside of the Golden Hour, and exhibits the overwhelming highlights and deep harsh shadows that are characteristic of images recorded near mid-day. The image was recorded using the Nikon D700 and the AF-S NIKKOR 24-70mm f/2.8G ED lens at 44mm. Exposure was f/16 at 1/125s, ISO at 200.
The image is pretty washed-out/over-exposed. Although we might have been able to do more with an exposure at -0.67 EV, there is little doubt that this image would most probably be more appealing, at least in the classic photographic sense, if it had been recorded between 19:00 and 20:00, since sunset on this date occurred at 20:00 (the image was recorded looking westward, e.g., into the rising sun, not a tractable shooting scenario). The problem was, as it often is, that I wasn’t there during the Golden Hour! Moreover, obviously most life occurs at sometime other than during the Golden Hour. Is there anything we can do to add more pleasing contrast and color saturation to such images? I certainly think so, otherwise I would have written this entry!
Let’s begin with a simple fix, which is to add a new layer on top of the original layer, and change the blending mode of the new layer to ‘Multiply’. Begin by dragging the Background layer to the copy layer icon, thus generating the Background copy layer as shown below:
Now change the ‘blending mode’ of the Background copy layer to Multiply as shown below – note that the pull-down menu tab contains a number of blending options – select the downward pointing arrow to the right of ‘Normal’ underneath the Layers tab to reveal them.
The result is shown below. I’d suggest that there may be no simple move that produces such a dramatically improved result as the addition of a Multiply-layer to a washed-out or overexposed image:
Finally, we can vary the extent of the blending of the top layer into the bottom layer by adjusting the opacity of the top layer.
I hope that you have found this entry to be useful. Good luck on your own efforts. Keep shooting, and don’t believe ‘em if they tell you you can’t make solid scenic color images outside of the Golden Hour.
Copyright 2010 Peter F. Flynn. No usage permitted without prior written consent. All rights reserved.
