Low-Light Options

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Today’s Question: When one is confronted with extreme low-light conditions, could you discuss the pros and cons of shooting at high ISO with in-camera high ISO noise reduction engaged versus purposely underexposing a photograph at lower ISO and subsequently correcting for the underexposure and reducing the noise during post-processing?

Tim’s Answer: When you raise the ISO setting in your digital camera, you are effectively under-exposing the photo, possibly to an extreme degree. Therefore, it is worth considering (as suggested in today’s question) how to minimize the risk of noise associated with that under-exposed photo.

The basic choice here is how to compensate for an under-exposed photo. Your two options are to either increase the ISO setting in the camera, or to leave the ISO setting at a low value (with a photo that is therefore underexposed) and save all adjustments for your image optimization workflow after the capture.

Put simply, you will generally get better results (often much better results) by raising the ISO setting as compared to simply under-exposing. To be sure, it is best to use the lowest ISO setting possible for the conditions in order to minimize the amount of noise in a given photo, because raising the ISO setting translates into amplification of the signal being gathered by the image sensor. That amplification translates to increased noise in the image.

However, while a high ISO setting increases the amount of noise in a photo, severely underexposing the image will produce (in most cases) far worse results. This was actually the subject of an article called “ISO Illustrated” that I published in the December 2013 issue of Pixology magazine.

I most certainly recommend keeping the ISO setting as low as possible to minimize noise. However, that doesn’t mean using a shutter speed that is too slow, or underexposing the image. When the situation requires a higher ISO setting to achieve a proper exposure, by all means raise the ISO setting. You may need to mitigate the noise in post-processing, and even with noise reduction the photo may not exhibit optimal quality. But the quality will still be better than if you had simply kept the ISO setting at a low value and under-exposed the photo.

Batch HDR

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Today’s Question: Is there any way I can batch process multiple image sets through HDR Pro in Photoshop, or am I restricted to one set at a time?

Tim’s Answer: In theory there are a few possible ways you might batch process your high dynamic range (HDR) captures using Photoshop or other HDR-processing software. However, I don’t recommend this approach, for two main reasons.

First, HDR processing can be rather labor-intensive. Especially when merging the data to a 32-bit per channel source HDR image (which then gets tone-mapped to produce the final result, or saved to be tone-mapped with other software), there is a tremendous amount of data being processed. In other words, it would be relatively easy to overwhelm even a very powerful computer system.

Second, when it comes to HDR processing there is tremendous variability in terms of the specific settings used for each set of photos. That is especially true when it comes to the tone-mapping phase of processing, where you’re applying adjustments and creative effects to the HDR image. However, it can also be an issue for the initial captures, especially as it relates to alignment, chromatic aberration adjustments, and ghosting removal.

Photoshop does not offer a batch-processing feature as part of the HDR Pro tool. I have seen some scripts that enable batch processing for HDR in Photoshop, and it is possible to batch-process images with Photomatix software as well (among other solutions, I’m sure).

But the bottom line in my mind is that you’re not missing anything, and that it is worth it (in my opinion) to “manually” process each set of photos for an HDR capture. I’ll add, by the way, that while HDR Pro in Photoshop does a good job of creating the initial HDR image, I consider other tools to be better at the tone-mapping portion of the process. For example, you can perform the tone-mapping work in Lightroom for a 32-bit per channel HDR image, or you might look at third-party products such as HDR Efex Pro (part of the Nik Collection from Google) for processing your RAW captures.

Online Publishing

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Today’s Question: I have a question about publishing to Facebook [from Lightroom]. When setting up all the parameters, I see once you have chosen an album. But you can’t change it? I may want to publish different pictures to different albums on Facebook. Can that be done via a single Facebook profile, or must I set up a separate profile for each album?

Tim’s Answer: It is true that once you have established a Publish Service for Facebook within Lightroom, you aren’t able to change the album to which that Publish Service is actually publishing. While this may seem odd, and it certainly can be a bit of an inconvenience, this limitation is based on the notion that the Collection that is used as the basis of publishing to Facebook is essentially synchronized with that Facebook album. Changing the target album could create a degree of confusion (or unintended consequences) with respect to the connection between Lightroom and Facebook.

You can, however, configure multiple Publish Services within Lightroom so that you have the option to publish to different albums on Facebook. You can create a new Publish Service by clicking the “plus” icon to the right of the Publish Services header on the left panel in the Library module and then choosing “Go to Publishing Manager” to bring up a dialog where you can establish the settings. Even easier, if you already have an existing Publish Service for Facebook, you can right-click on the header that says “Facebook” and choose the “Create Another Publish Service via ‘Facebook’” from the popup menu.

I think the thing to keep in mind here is that the Publish Services option to share photos on Facebook uses a synchronization approach. In other words, you aren’t simply posting a photo to Facebook from Lightroom, and then having Lightroom “forget” about the publication of the image. Rather, the photos you share are retained in a special Collection, and you can then review the photos you’ve published on Facebook using that collection. You can even interact with the comments for the photos on Facebook from directly within Lightroom.

Taken in this context, I think it is a little more clear why you can’t simply change the target album for the Publish Service for publishing to Facebook. For this reason, my general approach is to create a single album specifically for sharing from Lightroom, not intended to serve as an organizational tool within Facebook, but rather aimed at simply providing an easy way to share individual photos using Facebook.

Lens Correction

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Today’s Question: What is your opinion on using lens correction in Lightroom? Do you think it squishes the pixels around enough to have an effect on an images? I use it many times and have not seen any degradation in sharpness when using it.

Tim’s Answer: Overall I would say the various Lens Corrections adjustments in Lightroom’s Develop module (and the exact same adjustments in Adobe Camera Raw) produce excellent results that can greatly improve the overall appearance of a photo.

When it comes to the various perspective correction options, there’s no question that a close examination will show some degradation in overall image quality. You’ll generally see, for example, a slight reduction in sharpness in the areas that have been reshaped most significantly.

However, in my view, the very minor degradation in image quality is more than made up for by the benefits provided by the Lens Corrections adjustments. The chromatic aberration removal offers a tremendous improvement for images that need this work, the Upright controls can quickly straighten out an image that exhibits barrel distortion or perspective issues, and the Manual set of controls allow you to fine-tune the image to perfection.

In short, the various Lens Corrections controls can be invaluable when it comes to improving the overall look of a photo, and the problems they solve can represent significant issues for a photo. I never hesitate to make use of these various adjustment options for images that need the improvement.

Convert to DNG?

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Today’s Question: I use Lightroom and Photoshop and just bought a new Nikon camera. I can now shoot Raw format pictures. Since there are many Raw formats from the various Camera manufacturers and they are “non-standard” would you recommend converting to DNG format on import to Lightroom? What are the Pros and Cons of standardizing on DNG?

Tim’s Answer: The Adobe Digital Negative (DNG) file format was created as a publicly documented file format that can effectively replace the variety of proprietary RAW capture formats that have been created by camera manufacturers. In fact, a variety of digital cameras allow you to use the Adobe DNG format as an in-camera capture format to replace what would otherwise be a proprietary RAW capture format.

I don’t personally convert my RAW captures to DNG, for a few reasons.

First of all, despite the fact that there really aren’t any “real” reasons I should feel this way, I don’t feel comfortable deleting my original RAW captures after converting to the DNG file format. That means I would actually be increasing the amount of storage space used by my photos, since I would be keeping two copies (at least) of each image.

I also make use of a synchronization solution for backing up my photos (which I covered in an article in the September 2014 issue of my Pixology digital magazine). With this approach, the DNG file format represents a disadvantage when it comes to backing up my images. Any changes to metadata for a DNG file means the file itself is updated, and so the entire DNG file must be backed up again. With my approach of retaining the original RAW captures and saving metadata out to XMP “sidecar” files, the backup only needs to copy the small XMP file when I make changes to metadata for a photo.

In addition, I prefer to retain the “private” metadata that many digital cameras write into RAW captures. Granted, that data can generally only be accessed by using the RAW processing software from the camera manufacturer, but I like the idea of preserving any of that information just in case it becomes useful at a later date. It is possible to embed the full RAW capture in the DNG file to work around this issue, but that would also result in a rather large file compared to my original RAW captures.

There are, of course, some advantages to the DNG format. To begin with, as noted above, the DNG format is publicly documented, so that if the proprietary RAW capture format you would otherwise use is one day no longer supported by any software, you could still feel confident that the DNG format could be processed, even if new software had to be created based on the public file specification. This isn’t something I feel is of any significant concern, but some photographers feel differently.

Some photographers also prefer to have their metadata updates written into the single DNG file, rather than having those updates saved in a separate XMP sidecar file. As noted above, because of my approach to backing up my photos, the XMP approach is actually a benefit for me.
The DNG file format also provides a workaround for using software that doesn’t support the latest RAW capture formats. For example, perhaps you are using Adobe Camera Raw to process your RAW captures, but have an older version that doesn’t support a new capture format. You could use Adobe’s free DNG Converter software to convert those RAW captures to the DNG format, so they can then be processed with your older software.

Finally, the DNG file format produces files that are generally smaller than the original RAW capture, without actually losing any information, thanks to lossless compression. In general you can expect a DNG file to be about 20% smaller than the original RAW capture, though your specific results may vary.

Ultimately it is up to each photographer to choose whether a conversion to the DNG file format makes sense to them. I prefer to make use of the proprietary RAW capture format employed by the cameras I photograph with. But if your camera supports the DNG format, you could certainly use DNG as a capture format. And a variety of software tools allow you to convert to the DNG file format. The key is to consider the various advantages and disadvantages based on your specific workflow needs.

Partial Pixels

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Today’s Question: While I was watching one of your video lessons that covered sharpening in Photoshop, it struck me that you were using a value of less than one pixel to define the sharpening effect. How can a sharpening filter work on partial pixels?! Shouldn’t the value for the size (Radius) only be in whole numbers?

Tim’s Answer: I think the way I would describe this (understandable) source of confusion is that the number of pixels for the Radius setting is really a shorthand of sorts that goes beyond a simple number of pixels. In other words, you aren’t really having an effect that goes down to a level smaller than a single pixel, as that’s not possible with pixel-based editing. Instead, you are having an effect that is tapered across multiple pixels.

So, when you set the Radius to a value of a half pixel, you aren’t really having an effect on half of a pixel at a contrast edge, but rather are using a value of 0.5 as part of the (somewhat complex) formula that determines how much contrast is enhanced along existing contrast edges within the photo.

Keep in mind that the size of the sharpening effect (often referred to with a “Radius” value) interacts with the strength of the sharpening effect (often referred to with an “Amount” value). In addition, with many sharpening filters there are additional values you can adjust or factors that are used to determine exactly how the contrast enhancement of sharpening is applied to various areas throughout the image.

So, the Radius setting really relates to the size of the transition area for the contrast being enhanced. In some cases, with a very strong sharpening effect, the formula will cause a change with values that suggest granularity of one-tenth of a pixel. That’s not because the pixels are being divided into smaller units (they aren’t), but rather because the formula is blending the effect into the image. So in some ways you can think of the Radius setting as defining the degree of transition for the effect.

To get a sense of this, you can create a simple graphic in Photoshop. For example, create an image that is half black and half white, with a hard transition from black to white. Then apply a very slight blur to the image, so that there is a transition from black to white that spans perhaps ten pixels in the image. Then choose Filter > Sharpen > Unsharp Mask from the menu to bring up the dialog for the Unsharp Mask dialog (I recommend this filter for the test because it is a simpler sharpening filter than Smart Sharpen). Set the Amount to 500% (the maximum value) and the Threshold to 0 (the minimum value), and evaluate the effect in the image as you adjust the value for Radius.

If you conduct this little experiment, you’ll see that even a change of 0.1 or 0.2 pixels for Radius will have an impact on the sharpening effect in the photo, with higher values causing the gradation in the image to become smaller than they appear with a lower value for Radius. Again, this is just part of the complexity of the formula in play for this (and other) sharpening filters.

Filtering for No Keywords

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Today’s Question: I have a Lightroom question. I’m trying to either sort or find files that have no keywords in either a folder or collection. I know the symbol in the bottom right of the thumbnail but there’s no way to sort with that. Any suggestions?

Tim’s Answer: There is actually a very easy way to filter images to show only those that don’t have any keywords assigned to them. The icon you refer to is a “badge” indicating that keywords are assigned to a given image. While there isn’t exactly a filter based on the absence of that badge, there is a filter for “No Keywords”.

You can navigate to a specific folder containing the images you want to filter, of course. Then you want to view the Library Filter Bar, which can be enabled by choosing View > Show Filter Bar from the menu if it isn’t already visible. You can also use the backslash key (\) to toggle the display of the Library Filter Bar.

Next, to clear any existing filters, click the “None” option. Then click the “Metadata” option to display a set of columns that allow you to filter your images based on a variety of metadata values. Make sure all of the columns are set to the “All” option initially, so the images are not being filtered. Then click the header for the right-most column, and choose “Keyword” from the popup.

This will present a list of the keywords that have been assigned to any of the images that are currently available (in other words, the images in the folder you’re currently browsing). You will also find a “None” option on the list. Click that option, and the images will be filtered to include only those without any keywords assigned.

You could, of course, combine a variety of different filters in addition to the lack of keywords, in order to further refine the range of photos being displayed. But as you can see, it is quite simple to filter a set of photos in Lightroom to include only those without keywords assigned to them.

Camera Connection

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Today’s Question: Why do you remove the card from the camera when downloading photos as opposed to leaving the card in the camera, connecting the camera to the computer and downloading and deleting the photos without ever touching the card?

Tim’s Answer: There are two key reasons I never connect my camera to my computer for purposes of downloading photos.

The first reason relates to download speed. In most cases connecting your camera directly to your computer will result in a slower download speed than if you use a good card reader with a high-speed connection. Your actual results vary, of course, based on the capabilities of your specific camera model (such as the type of connection available) and based on the type of card reader you might use. But in general, you can download more quickly with a card reader than you can with your camera connected to your computer.

The second reason is the “real” reason for my personal decision to never connect my camera to the computer for downloading. Put simply, I’m afraid I’ll end up knocking my camera onto the floor. I’ve been accused of being a little clumsy at times, and I’m pretty sure I would end up snagging the cable connecting the camera to the computer, sending the camera flying off the table to the floor.

I’ve heard photographers express concern about damaging their camera by repeatedly removing and inserting media cards, and this is certainly a valid concern. I have seen more than one camera with bent pins caused by a CompactFlash card that didn’t get inserted quite right, for example. But with proper care I don’t consider this to be a significant concern. At least for me personally, I think the bigger risk involves knocking the camera off the table.

So, that’s my reasoning. But ultimately I would say that there isn’t an especially strong argument either way, unless downloading as quickly as possible is the highest priority for you. If speed is critical, I recommend using the fastest cards and the fastest card reader available, instead of downloading directly from the camera. But otherwise, as far as I’m concerned this is really a matter of personal preference.

Pixel Grid

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Today’s Question: When I zoom in really close on a photo in Photoshop, I can see grid lines outlining every pixel. I find this very distracting. Is there a way to turn it off?

Tim’s Answer: The grid lines you are referring to are the “Pixel Grid” display option in Photoshop, which is enabled by default. I too find those grid lines to be rather distracting, and most of the time I prefer not to see them. So, I keep the Pixel Grid turned off, and turn it on temporarily when I feel it will be helpful.

You can disable (or enable) the Pixel Grid display in Photoshop by choosing View > Show > Pixel Grid from the menu. When a checkmark icon is shown to the left of Pixel Grid on the menu, that is an indication the feature is enabled. When you turn the Pixel Grid off, the checkmark icon will disappear along with the grid display you’ve been seeing when you zoom in on your photos.

Dye Sub Printers

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Today’s Question: What, if any, are the downsides to owning a nice dye sub printer for professional output? I wonder why nobody talks about these printers. From my experience they are “picture perfect” and would be hard pressed to see any difference between a dye sub print or a film print (not digital) but I wonder about the ink-jet vs dye sub as well. What am I missing? Even my local Wal-Mart uses dye sub printers for their “professional” output.

Tim’s Answer: As with just about any comparison between two categories of products, when it comes to evaluating dye sublimation (or “dye sub” for short) printers there are both advantages and disadvantages. In my opinion, it is entirely plausible that dye sublimation printers could have originally become the most popular way for photographers to print their images, but instead photographers favored photo inkjet printers.

Let’s first consider some of the advantages of dye sub printers.

Dye sub printers get their name from the process of sublimating solid dye into a gaseous form and impregnating that dye into the surface of the paper being printed to. This produces several significant benefits.

Dye sub prints are truly continuous tone, rather than being made up of a series of tiny “dots” as is the case for photo inkjet printers. That results in smoother transitions of tone and color, and higher perceived quality. Of course, recent inkjet printers are capable of producing such tiny ink droplets that they can be thought of as being virtually continuous tone, but that wasn’t the case with earlier inkjet printers.

Because of the way solid dyes are sublimated into the surface of the paper, dye sub prints are also generally more durable than photo inkjet printers. For example, the prints from dye sub printers are better able to withstand being exposed to water, almost to the point that you could consider a dye sub print to be “waterproof”.

Of course, there are some disadvantages to dye sub printers as well, and I believe these are the primary reasons these printers did not become more popular with photographers early on in the history of photo printers. It should be noted that it is altogether possible that if dye sub printers had been more popular early on, they would have also been more profitable and therefore manufacturers might have invested money to improve upon these shortcomings.

Dye sub printers are generally slower compared to most photo inkjet printers, although some of the top-end dye sub printers will perform on par with many inkjet printers.

Dye sub printers are more limited in size, with the ink ribbon cartridges being matched to the paper size. In general you can think of a dye sub printer as only supporting a single print size. Thus, dye sub can be a great option for producing a large number of 4×6 photo prints, but not a good solution for photographers who need to print at a wide variety of sizes.

Dye sub printers also tend to be more expensive than photo inkjet printers in terms of overall operation. This, again, is probably mostly due to the very large market for photo inkjet printers compared to the smaller market for dye sublimation printers.

As you may have gathered by now, the limitations of dye sublimation printers relate more to a lack of flexibility, which is probably the primary reason that photo inkjet printers gained much higher adoption rates than dye sublimation printers. That said, dye sub printers are still an excellent choice for certain applications. If a dye sub printer suits your specific needs, I would certainly not hesitate to make use of such a printer. That said, you may very well find that a good photo inkjet printer will also be able to meet your specific needs, with additional flexibility as a bonus.