Author: Tim Grey

Today’s Question: If a digital camera only captures color for each pixel, then where does the final image obtain full color information?

Tim’s Quick Answer: For cameras that capture only one color value (generally red, green, or blue) for each photosite (pixel), the “other” color values for each pixel are calculated based on the values from neighboring pixels.

More Detail: Most cameras do not capture full color for each pixel in a photo. Rather, they capture a single color value for each pixel, and the “other” color values need to be calculated either at the time of capture (for a JPEG capture) or in post-processing (for a raw capture).

Most cameras capture in RGB (red, green, blue) color and use a Bayer pattern sensor array. That means for each grid of four pixels, one pixel will record only red light, two pixels will record only green light, and one pixel will record only blue light.

If you think about the notion of capturing only one of the three necessary color values for each pixel, it might seem implausible that full color details could be calculated for the photo. However, I think it can be helpful to try to envision what each individual color channel would look like.

For example, the red and blue channels are only represented by one-quarter of the pixels on the image sensor. Imagine you are viewing that image, where three-quarters of the pixels are blank, but you know what one-quarter of the pixels look like. What you have is a relatively course image, but an image nevertheless.

You can probably then envision how it is possible for sophisticated software to “fill in the blanks” in the empty pixel values. This is easiest for the green channel where half of the pixels have values, and so you only need to fill in the other half. But even for the red and blue channels, this can obviously be done quite effectively.

Today’s Question: If you expand many subfolders contained within parent folders in the Folders list in Lightroom Classic, is there a trick to collapse them all at once?

Tim’s Quick Answer: If you hold the Alt (Windows) or Option (Macintosh) key while clicking on the arrow to expand or collapse a parent folder, all subfolders below that parent folder level will also be expanded or collapsed.

More Detail: In Lightroom Classic the Folders list on the left panel in the Library module reflects the folder structure on your hard drive for those folders that contain photos being managed by Lightroom Classic. Therefore, you can have folders with subfolders represented in Lightroom Classic, including multiple layers of subfolders depending on how you have defined your folder structure.

You can expand or collapse a folder to reveal or hide subfolders by clicking on the triangle icon to the left of a parent folder. However, you can expand or collapse all subfolders in a single step by holding the Alt/Option key while clicking on the triangle icon for the parent folder.

Let’s assume a date-based folder structure, where you have a folder for each calendar year. Within each year folder you have folders for each month, and within each month folder you have folders for each day.

By default, if you simply click to expand the year folder, you’ll only see the month folders within that year folder. You would need to click the triangle to the left of a month folder to see the day folders contained within that month folder.

However, you can hold the Alt/Option key will clicking the triangle for a parent folder to expand or collapse all subfolders at all levels below that parent folder. So, for example, if you have expanded some of the month folders within the year folder, you could Alt/Option click on the triangle to the left of the year folder to collapse all folders. If you then click on the triangle to expand, you’ll once again only see the month folders.

You can also expand all folders in this way. So, rather than simply clicking on the triangle for the year folder to expand that folder, you can Alt/Option click on the triangle and you will then see all of the month folders and all of the day folders are visible because all subfolders have been expanded.

So, using this Alt/Option keyboard shortcut can be helpful for quickly reducing clutter for the folder display, and also for quickly revealing all levels of folders in a particular location.

Today’s Question: I know you wear glasses and I also wear glasses, but they are “progressive” lenses. As a result, I often seem to have trouble getting manual focus exactly right. What would your advice be? Should I get a standard pair of reading glasses or a prescription just for photography?

Tim’s Quick Answer: I would recommend using a pair of reading glasses when focusing manually, using live view on the camera’s LCD display to evaluate the focus. If you prefer to focus through the optical viewfinder, I recommend getting a pair of glasses with a single distant-vision prescription rather than using progressive lenses.

More Detail: My eyeglasses do have progressive lenses, so I have dealt with this challenge firsthand. It can be challenging to make sure you’re looking through the right area of the lens to ensure your vision is sharp for evaluating manual focus.

I find the use of live view on the camera’s LCD display tremendously helpful for accurate manual focus. Most cameras enable you to zoom in with this live view display, so you’re able to get an even closer look at the area of the scene you want to use for evaluating focus. Since you would therefore be viewing the LCD from a close distance, reading glasses work very well in terms of avoiding the challenge of progressive lenses.

If you prefer to adjust focus by looking through the optical viewfinder, you’ll likely need distance vision correction, since your eyes will be focusing at the same distance as the subject. In this case you would likely find it easiest to have eyeglasses with a single prescription to correct your distant vision.

It is also worth noting that you may be able to apply enough of a diopter correction to the viewfinder (if your camera includes a diopter adjustment) to compensate for your vision so you could use the viewfinder for manual focus without wearing your eyeglasses at all. When adjusting the diopter setting, you can evaluate the text and symbols projected by the camera in the viewfinder. When the text and symbols appear sharp, you’ve achieved the proper diopter adjustment.

Today’s Question: Are the slider values in applied presets in Lightroom Classic saved as part of the image or is the preset itself saved with the image.? In other words, after applying a preset to an image, if you change the preset will the image automatically change to reflect the new settings for the preset?

Tim’s Quick Answer: When you apply a preset to an image in Lightroom Classic, the settings from that preset are applied to the image. Changing a preset after it has been applied to an image will not cause that image to be updated based on changes to the preset.

More Detail: Presets in the Develop module in Lightroom Classic preserve specific settings from the various adjustments available on the right panel. When you create a preset you can choose which adjustments you want to include, and those adjustments will reflect the settings for the current image in the Develop module.

You can update a preset by changing the settings on the right panel in the Develop module, then right-clicking on the preset in the Presets section on the left panel and choosing “Update with Current Settings” from the popup menu. However, this will not cause any changes to the images you previously applied the preset to.

For example, let’s assume you created a preset that converts an image to a black and white interpretation. You apply that preset to an image, and the image is converted to black and white. If you later update that preset to include a color tint, such as a sepia-tone effect, applying that preset to an image will obviously cause it to have a monochromatic color tint.

However, images you had previously applied the preset to would still appear in black and white, not with a sepia-tone effect, unless you re-applied the preset to the image. Changing a preset does not automatically alter the appearance of photos you had previously applied that preset to.

Today’s Question: My “L” hard drive failed, but I had backed it up to another drive named “K”. Can I just rename the “K” drive letter to “L” and go on with life (and then back up the K drive to an extra disk?). I ask because I got a warning message that says, “some drive programs that rely on letters may not run correctly, do you wish to continue…”.

Tim’s Quick Answer: Yes, provided the backup drive represents an exact match of the original drive at least in terms of photo storage, you can indeed just change the drive letter (or volume label for Macintosh users) and continue using the backup drive in place of the original (making a new backup as soon as possible of course).

More Detail: This type of scenario is exactly why I prefer a synchronization approach to backing up my photos and other important data. When you’ve created a backup drive that matches the source drive, it is very easy to recover from that failure.

With a synchronization approach to backup, the file and folder structure on the backup drive will be an exact match of the source drive. So, if the source drive fails, you can simply use the backup drive in its place.

In the context of Lightroom Classic, however, you’ll need to make sure that the drive itself appears as an exact match. That means for Windows users the drive letter must be updated for the backup drive to match the original drive. For Macintosh users that means changing the volume label (by renaming the drive) so that it matches the original.

The warning about a mismatch effectively describes why the backup drive wouldn’t work without this update. If you changed the drive letter or volume label of your original hard drive, Lightroom Classic would no longer be able to find the photos where they were expected. In this case it is sort of the opposite. The backup drive already represents a mismatch, so you need to change the drive letter or volume label to correct the mismatch.

Once you correct that mismatch, everything will appear normally within Lightroom Classic. Of course, you should also make sure to create another backup of your photos as quickly as possible after a hard drive failure.

I happen to use software called GoodSync to back up my photos with a synchronization approach. This provides exactly the benefits described above. You can learn more about GoodSync software here:

http://timgrey.me/greybackup

Today’s Question: Regarding your response to the question on printer tonal range, you say to evaluate the test image under a bright light source. I wonder if one shouldn’t evaluate the test image under a light source, and at a distance, that provides a luminance value similar to that expected in the location where the print is most likely to be displayed?

Tim’s Quick Answer: In the context of evaluating the actual tonal range capabilities of your printer, I recommend using a very bright light source so you can better evaluate the print. That said, when it comes to a final print you intend to hang on the wall, it is most certainly reasonable to optimize the print based on those display conditions.

More Detail: From time to time I’ve written about an issue whereby a printer doesn’t actually render complete shadow detail in the darkest shadows, even when you’ve used an accurate printer profile to produce the print. You can compensate for this behavior by first evaluating the behavior of your printer, and then applying a compensating adjustment before printing.

You can read about the process, and download a target image used to evaluate the behavior of your printer, in an article on the GreyLearning blog here:

http://greylearningblog.com/printer-tonal-range-correction/

While it is perfectly reasonable to evaluate an individual print based on the conditions under which it will be displayed, when it comes to compensating in general for the tonal range limitations of a printer, I don’t recommend that approach.

To establish a baseline compensation that will ensure your prints contain all of the shadow detail possible, you should evaluate the test print under a bright light source. This enables you to determine the actual behavior of your printer (specific to the paper and ink combination being used with that printer) in terms of rendering shadow detail.

The result of this testing would provide you with a general compensation adjustment that could be applied to every photo you print. In cases where you know the precise conditions under which a print will be displayed, you could go a step further and evaluate that print under those conditions. You could then apply a compensation specific to that print based on the display conditions intended for the print.

Of course, it is important to keep in mind that if you apply adjustments to compensate for the specific conditions under which a print will be displayed, if that print is moved to a different location it may not look its best. The specific results depend on the lighting conditions, and in particular to how significant the differences in lighting conditions actually are.

Today’s Question: I’d like to print the photo to fit in a frame that has a 2″ matting all around. I don’t want to clip any of the photo, and I don’t want any of the blank border of the print to show once mounted in the frame with a 2″ matting. How do I account for the output photo size being mounted in a frame with matting?

Tim’s Quick Answer: In general, you just need to make sure that there is some blank paper around the edge of the actual image printed on the page, to allow for the matting of the print. However, it is important to keep in mind that it is difficult to add matting accurately right up to the edge of the actual image area, so you’re going to need to allow for at least a tiny bit of cropping caused by the matting.

More Detail: When matting a photographic print, the print is attached to the mat board. This requires that there is “extra” paper around the edge of the printed photo. In general, about half an inch of space all the way around the print will be adequate. You can achieve this “extra” space by printing the image at the size intended, but doing so on a larger sheet of paper. For example, you could print a 11”x17” image on a 13”x19” sheet of paper.

However, it is important to keep in mind that you should expect the mat board to cover at least a tiny portion of the outside edge of the printed photo. A skilled mat cutter can minimize the amount of image that gets cropped in this process, but it is very difficult to have a cut mat edge perfectly follow the edge of the printed image on the page.

An alternative, such as you might use when a signature is on the paper area outside the printed photo, would be to “float” the image within the mat. In other words, you could have the mat cut larger than the actual printed photo area, to leave some white space.

If your aim is to have minimal cropping of the photo, you may want to print the photo slightly larger (about a quarter of an inch wider and taller) than the intended image area size within the mat. Alternatively, you could simply print to the intended size, and then ask the mat cutter to cut a custom mat that matches the image size as closely as possible with minimal cropping.

Today’s Question: One step in Lightroom Classic I make in almost any post-processing is to sharpen using the Masking slider with the Option key [Alt key on Windows] held down. This lets me control how much of the image I am sharpening, but often I like the abstract black-and-white result that appears in the preview. Is there a way using LR or Photoshop to replicate the effect and to be able to turn that into a printable image?

Tim’s Quick Answer: You could capture a screenshot of this effect, using a timer option while making sure that the preview image is as large as possible to ensure maximum resolution for the resulting image.

More Detail: You can capture a screenshot of the screen display on your computer to preserve whatever is displayed on the screen. This can be a little tricky, however, when you need to use special keyboard shortcuts to make the intended display appear, such as the case with the example in today’s question. However, you can use a timer feature to capture a delayed screenshot, enabling you to apply the required keyboard shortcut before the screen is actually captured.

For example, I use the Screenshot utility included in the Macintosh operating system when I need to capture screenshots with a timer delay. Windows users can use the Snipping tool included with Windows 10 for this purpose. Both enable you to apply a time delay to the screen capture.

So, you could for example configure a five second delay for the screen capture. Get the screen configured overall, including in this case making the preview image as large as possible by hiding all but the right panel in the Develop module, for example. Make sure you’re ready to apply the keyboard shortcut that is required, and then initiate the screenshot.

While the timer is counting down, you can configure the display. In this case that would mean holding the Alt/Option key and clicking and holding the mouse on the Masking slider for the sharpening controls found in the Detail section of the right panel in the Develop module. Hold the key and mouse button until the screenshot is captured.

You can then open that screenshot in Photoshop, for example, to crop and otherwise optimize the image to your liking.

Today’s Question: If you lose the Lightroom Catalog you lose virtual copies even if you are using XMP files, which saves the adjustments made to the original image file. But is there any way to save the virtual copy with all the adjustments made to that virtual copy?

Tim’s Quick Answer: To preserve a virtual copy outside of the Lightroom Classic catalog, you would need to either create a copy of the source raw capture or create a new derivative image. That copy could be added to the catalog alongside the original, providing two copies of the same image rather than using a virtual copy for this purpose.

More Detail: Virtual copies in Lightroom Classic enable you to have more than one interpretation of the same source image. For example, you could apply adjustments to a raw capture with a color interpretation, then make a virtual copy and create a black and white interpretation of that image. Both versions of the image you see in Lightroom Classic would represent a set of adjustments applied to the same source raw capture.

However, virtual copies are only preserved within the Lightroom Classic catalog, so if you lost your catalog you would lose your virtual copies. You could overcome this issue by using an additional copy of the source raw image in place of a virtual copy. This obviously involves consuming more storage on your hard drive, but it also means you would not lose the additional version of the raw capture if you lost your Lightroom Classic catalog.

To create an additional copy of the source raw capture to apply different adjustments to, you could use the Export feature in conjunction with the option to add the exported image to the current Lightroom Classic catalog.

Start by selecting the source raw capture and clicking the Export button at the bottom of the left panel in the Library module. In the Export Location section of the Export dialog, choose “Same folder as original photo” from the Export To popup, and turn on the “Add to This Catalog” checkbox. In the File Settings section, choose Original from the Image Format popup.

Click the Export button to export a copy of the raw capture to the same location, with that copy added to the current catalog. Because you are exporting the image to the same folder location, there will be a filename conflict. In the dialog that appears to indicate this conflict, click the “Use Unique Names” button. This will create a copy of the selected image with the same base filename, but with a number (such as “-2”) appended to that filename.

At this point you would have two copies of the original raw capture in the same folder in your Lightroom Classic catalog. You could then apply unique adjustments to each version of the image. This provides the same basic capability of using virtual copies to create multiple versions of the image, though of course with more hard drive space being consumed in the process. But again, with this approach you would maintain both copies of the image even if you lost your Lightroom Classic catalog, which would not be the case with virtual copies.

Today’s Question: As I was looking up the number of aperture blades on my lenses, I saw a specification that made me wonder: Do the number of lens elements and number of groups have any effect on bokeh, starburst or other aesthetics?

Tim’s Quick Answer: The “simple” answer here would be that no, the number of lens elements or groups of elements wouldn’t have an impact on the creative aesthetic effects produced by a lens. Of course, the real answer is far from simple.

More Detail: There are a variety of factors that impact how many individual lens elements are included within a camera lens. However, aesthetic factors such as the bokeh or starburst effect would not be significantly impacted by the number of lens elements or groups.

What we call a “lens” in photography is actually a piece of sophisticated equipment that includes multiple lens elements. As a very general rule, better image quality and greater light transmission is achieved with fewer lens elements. However, that’s not to say that fewer lens elements will translate to a better lens.

More lens elements are also required to correct for distortion in a lens. In this respect, more lens elements can mean that the overall image quality will be improved, at least in terms of distortion. These types of corrections will often involve pairs of lens elements, which form an individual group of elements. So you can get some sense of the degree of correction being applied within the lens by the number of groups.

However, while the generalizations above may often be true, they are not accurate across the board and therefore can’t be used reliably to make a decision about lens quality or aesthetic results. In other words, I would generally recommend ignoring the number of lens elements and groups, and instead focus on other methods of determining the results you can achieve with a lens, such as reviews the delve into details such as the resolving power of the lens.