Ask Tim Grey

Today’s Question: Was the photo of the sunset in Rome that you shared on Instagram an HDR? How did you get so much detail in the shadows while still having detail in the sun?

Tim’s Quick Answer: Yes, the Rome sunset photo in question (https://www.instagram.com/p/BaEWah8ANR2/) was a high dynamic range (HDR) image, consisting of seven exposures separated by one stop each.

More Detail: When you include the sun in the frame, you can count on either losing detail in the foreground shadow areas or losing detail in the sun (or both). By capturing multiple exposures and blending them together into an HDR result, you can retain considerable detail in both the highlights and the shadows and then determine how you want to interpret the scene.

My general approach to capturing the exposures for an HDR image is to determine exposure settings that will retain highlight detail for the brightest areas of the image, and then increase the exposure from there to cover the full range of shadow values.

In the case of including the sun in the frame, I don’t generally go to the extreme of including full detail in the sun. I will typically allow the red channel to get blown out to some extent, for example, so that I’m retaining reasonable detail but not capturing a huge range of images.

You can use automatic exposure bracketing to capture the sequence of images, or use the Manual exposure mode to adjust the shutter speed for each capture. I usually start with a dark exposure that retains highlight detail, and then continue increasing the exposure in two-stop increments until I have an exposure that retains full shadow detail. (And yes, in this specific example I was only bracketing in one-stop increments, only because I didn’t need more range for this specific range and prefer to adjust the increments rather than change the number of exposures).

The images can then be assembled into an HDR image using a variety of different software tools. In the final tone-mapping step of the workflow you can choose how to interpret the final scene. At this point I recommend applying adjustments that preserve detail and yet retain a natural look to the image.

Today’s Question: You have recommended having an individual folder for each photo trip. But what about when you visit the same location more than once, and you want to be able to browse all of the photos from that location from multiple trips? How can you browse all of the images in Lightroom if the photos are in different folders?

Tim’s Quick Answer: You can simply browse the contents of multiple folders in Lightroom by selecting more than one folder from the Folders list on the left panel, and applying any filters you’d like to determine which photos within the multiple selected photos you’ll actually be browsing.

More Detail: I’ve found that many Lightroom users don’t realize they can select more than one folder from the Folders list on the left panel in the Library module, in order to browse the photos contained in multiple folders.

You can start by clicking on one of the folders you’d like to browse, within the Folders list on the left panel in the Library module. If the multiple folders you want to browse are all in a row, you can then hold the Shift key on the keyboard while clicking on the name of the last folder among those you want to browse. If you want to select folders that aren’t all in a row, you can hold the Ctrl key on Windows or the Command key on Macintosh while clicking on individual folders to toggle the selection of each folder on or off.

As you select more than one folder, you’ll be browsing the images contained in all of the selected folder. If you then apply a filter (such as for images with a star rating) you will only see the images from all of the selected folder that match the filter criteria you’ve established.

Today’s Question: I know you’ve covered this before, but can you remind me how to create a selection from a color channel in Photoshop?

Tim’s Quick Answer: You can create a selection based on a color channel by first duplicating the applicable channel, increasing contrast for that channel, and then cleaning it up as needed. You can then load a selection based on the duplicate channel you worked on.

More Detail: In many cases creating a selection based on one of the three color channels (red, green, or blue) can provide a quick way to isolate a specific subject in a photo. Even in situations where there isn’t much contrast in tonality, even a small amount of color contrast can enable you to create a good selection quickly, and then refine as needed from there.

To get started, go to the Channels panel (you can choose Window > Channels from the menu if the Channels panel isn’t visible) and decide which channel contains the best contrast for the area you want to select. Then drag the thumbnail for that channel to the “New Channel” button (the blank sheet of paper icon) at the bottom of the Channels panel.

Next, apply a Levels adjustment to maximize contrast to the extent possible for the duplicate channel you created. Start by choosing Image > Adjustments > Levels from the menu. Then in the Levels dialog drag both the black point and white point sliders below the histogram inward in order to maximize contrast to define the subject you want to isolate. For example, if you were trying to isolate the sky you would want to drag the sliders inward until the sky is white and the rest of the image is black for your duplicate channel.

You can also perform some cleanup work at this point, such as by using the Brush tool to paint with black or white in order to clean blemishes within the areas you have defined through contrast on the duplicate channel.

When you’re ready to load a selection based on the duplicate channel you’ve refined, you can simply click the “Load Selection” button (the dashed circle icon) at the bottom of the Channels panel. Then click the RGB thumbnail to return to your full color image, and you can employ the selection as the basis of a layer mask for a targeted adjustment or composite image.

Today’s Question: As a follow-up question, what if the intent is not to make an HDR [high dynamic range] image, but rather to “hand blend” different exposures with layers and masks in Photoshop? What would your advice be about capture sharpening in Lightroom prior to opening as layers in Photoshop to blend multiple exposures?

Tim’s Quick Answer: When you send raw captures from Lightroom to Photoshop I recommend that you apply capture sharpening first within Lightroom, since the individual raw captures will be rendered to pixel values as part of this process.

More Detail: When assembling an HDR (high dynamic range) image from multiple raw captures, I prefer to minimize the amount of processing performed, as noted in an Ask Tim Grey eNewsletter last week:

https://asktimgrey.com/2017/10/05/sharpening-for-hdr/

When you are processing individual images to be assembled into a layered document in Photoshop, I recommend performing your initial processing in Lightroom (or Adobe Camera Raw) before creating the layered document.

In other words, I prefer to fully leverage the raw capture to ensure optimal image quality before rendering the raw captures to pixel values for the final composite.

The difference here relates to how the pixel values are being processed. When you assemble an HDR image you aren’t simply using a layer mask to combine different tonal values from different exposure. Rather, you are essentially combining all of the exposure information into a single file with tremendous tonal range, and then processing that HDR result via tone-mapping to produce a “normal” photographic image with greater detail than could be accomplished with a single exposure.

When creating a layered image in Photoshop you will actually render the pixel values and then blend the images based on visibility defined by a layer mask. The individual pixels are assembled in a way that is quite different from HDR processing. As a result, with a layered document I prefer to process the images to an optimal appearance before assembling.

So, for HDR images I prefer to minimize processing applied before assembly of the HDR image, while for composite layered images I prefer to process (including the application of capture sharpening) to create optimized images to be assembled into a layered image.

Today’s Question: I’m confused about the difference between the Detail and Masking sliders for sharpening in Adobe Camera Raw [or Lightroom]. They sound like they do the same thing. Can you clarify?

Tim’s Quick Answer: You can think of the Detail slider as providing the ability to expand the sharpening effect to the finest details in the image, even if that detail represents a relatively smooth area of the photo. The Masking slider enables you to prevent sharpening from applying to areas of minimal contrast, helping to ensure smooth areas of the photo remain smooth.

More Detail: The Detail and Masking sliders are found with the sharpening controls in both Adobe Camera Raw and Lightroom, and the controls operate the same in both software tools. In some respects you can think of the Detail slider as the “I really want to bring out the maximum detail” slider, and the Masking slider as the “It is important that smooth areas of the image remain smooth” slider.

In other words, you might think of these sliders as providing the opposite effect for your image. However, it is important to keep in mind that there are certainly situations where you might increase the value for both sliders. Doing so enables you to really maximize the enhancement of fine detail, while preventing the effect from applying to the areas of smoothest texture in an image.

Sharpening is a process of enhancing contrast where contrast already exists. In other words, in concept you are enhancing the contrast that defines areas of texture and detail in an image. Increasing the value for the Detail slider enables you to push beyond the default level of sharpening, to enhance texture for the finest levels of detail within the photo. Reducing the value of this slider to the minimum value of 0 will scale back the sharpening so that fine detail is not accentuated as much.

Increasing the value for the Masking slider will prevent the sharpening effect from applying to relatively smooth areas of the image, to help ensure those areas remain smooth, and that noise and minor textures are not enhanced.

With both the Detail and Masking controls you can hold the Alt key on Windows or the Option key on Macintosh while dragging the slider in order to see a preview that can help you better establish the optimal setting for the image you’re working on.

And to learn even more about sharpening, you might be interested in my “Understanding Sharpening” course available through the GreyLearning library here:

https://www.greylearning.com/courses/sharpening

Today’s Question: Can you give tips for those of us that don’t have automatic exposure bracketing on our cameras, for capturing an HDR [high dynamic range] image?

Tim’s Quick Answer: As a general rule, if you don’t have automatic exposure bracketing (AEB) as a feature of your camera, you can set an initial exposure in Manual mode and then adjust the shutter speed by two stops for each subsequent exposure until the full tonal range of the scene has been captured.

More Detail: The key to creating a final HDR image that includes the full range of tonality from the original scene is to capture enough images with varying exposures to cover the full range of tonal values within the scene.

When you are using automatic exposure bracketing, this process is generally quite simple. It can be similarly simply when you need to capture each frame individually, provided you take a consistent approach to this process.

I recommend first capturing an image that is dark enough to retain full detail in the brightest areas of the scene. You can use an automatic or semi-automatic exposure mode to determine the best exposure settings if that is easier for you. Then dial in those same settings in the Manual exposure mode.

After capturing the first image in Manual exposure mode, with settings that preserve highlight detail, you can increase the exposure time (use a longer shutter speed) by two stops for the next capture. For example, if you have your camera set to adjust the exposure in one-half stop increments, you can turn the dial that adjusts shutter speed by four “clicks” to increase the exposure time.

Repeat this process of capturing an image and then adjusting the shutter speed by two stops, until the histogram shows that you have captured an image that retains full detail in the darkest shadow areas. I will often actually capture an image that is even brighter than necessary, in order to help minimize noise in the dark shadow areas of the scene.

With this “manual” approach, and with a little practice, you can quickly and easily capture a sequence of images to create an HDR image, even without the benefit of automatic exposure bracketing.

Today’s Question: Would it be good to minimize capture sharpening, including the sharpening applied by default in Lightroom [or Adobe Camera Raw] until after merging multiple exposures into a high dynamic range [HDR] image?

Tim’s Quick Answer: In general I do recommend that you minimize sharpening for the initial captures that will assembled into an HDR image, although in actual practice this depends on the specific workflow (and software) you’re using to assemble the initial HDR image.

More Detail: In many cases when you assemble an HDR image, each original raw captures is rendered to produce full pixel values for the high dynamic range result. As a result, it can be advantageous to ensure those original captures have minimal adjustments, or at least only adjustments that will be beneficial.

When it comes to sharpening, I prefer not to apply sharpening to the initial captures as part of this process. In other words, I want to combine the pixel values based on the original capture data, and then apply sharpening and other corrective adjustments after the HDR image has been created.

With some software the issue of minimizing initial processing is not actually a factor. For example, if you process several exposures into an HDR image using the “Photo Merge” feature in Lightroom, the resulting image will be an Adobe DNG file with any prior adjustments stored as metadata. In other words, prior adjustments won’t actually harm an HDR image created in this way.

As a perhaps more dramatic example, if you convert the original captures to black and white in Lightroom, and then merge those black and white captures to an HDR image in Lightroom, the HDR image will also be black and white. However, because the adjustments you applied are actually just metadata values, you can switch to the Color setting for the Treatment control in the Basic set of adjustments, and the black and white HDR image will return to the original color from your original captures.

So, as a general concept I recommend minimizing the processing you apply to the raw captures you will merge into an HDR result. However, in some cases this issue is not a concern based on the workflow of certain software (such as Lightroom) when creating the initial HDR image.

Today’s Question: One thing that I wish Lightroom would do is manage variants of files that I work in Photoshop to take advantage of it’s sharpening and editing capabilities. For example, the original Photoshop file might be a TIFF that I create in the ProPhoto RGB color space with the intent of printing it. But then I might want another in the sRGB color space at a lower resolution to enter in a contest. Lightroom would track the first file but the second one, created with Save As, wouldn’t be tracked unless I have Lightroom sync the folder.

What’s the most efficient way to keep the Lightroom catalog current when Save As is required?

Tim’s Quick Answer: This is one of the reasons I strongly recommend not using the “Save As” command when working with an image you have sent to Photoshop from Lightroom. I would either send the source image to Photoshop separately for each derivative image you need to create, or leverage the Export command when that suits your specific needs (such as when creating a JPEG image).

More Detail: When you use the Save As command in Photoshop after sending a source image to Photoshop from Lightroom, in most cases the resulting derivative image file will not be included in your Lightroom catalog. Only the initial derivative saved with the “Save” (not “Save As”) command will be included in your catalog.

There are several ways you could work around this, including the “Synchronize Folder” command available when you right-click on an existing folder within Lightroom.

For images you need (or want) to work on in Photoshop for any reason, I recommend using the “Edit In” command in Lightroom (found on the Photo menu) for each derivative image you want to create. I also generally use the original source image for creating each of these derivatives. So, for example, you could send the original image to Photoshop for the TIFF you want to create for printing, and then use the “Edit In” command a second time to create a JPEG for other purposes.

In many typical scenarios for sharing images, you might also simply use the Export command to create your derivative image, adding the resulting image file into your Lightroom catalog as part of the process. Within the Export dialog you can configure the output settings as needed, such as by choosing the JPEG image file format with the option selected to convert that image to the sRGB color space. You can also then turn on the “Add to This Catalog” checkbox in the Export dialog, so that the derivative image you are creating (and presumably saving in the same folder as the master image) will be added to the Lightroom catalog as part of the export process.

You might also consider simply not saving the derivative images at all in most cases. With very few exceptions, when I am creating output in any form, I will initiate the process with my “master” image. That might be the original capture included in my Lightroom catalog, or it might be a TIFF or PSD image I’ve created using Photoshop. In either case, that “master” image is generally the starting point for any output I want to create. In other words, in most cases I don’t need to retain all of the various derivatives I might create within my workflow, since I will usually start the process of sharing a photo by using the master image file rather than a derivative copy.

Today’s Question: I have a black & white film negative. How do I convert it in Photoshop or Lightroom to print an image?

Tim’s Quick Answer: For a black and white film negative I recommend first scanning the film in color, then converting to black and white and optimizing for the final print.

More Detail: As a general rule it is best to work with a full-color image even when your intent is to produce a black and white final result. That is because the color version of the image will have more information to work with, which in turn can help you produce a final image with greater detail and overall quality.

Of course, with a black and white negative it might seem a little silly to scan the film as a color image, since in concept the film doesn’t contain any color. However, there is generally at least a slight degree of color in the film, even if that is only the “orange mask” that is added to some films. Naturally you will also want to be sure to (in general) scan at the highest optical resolution of the scanner being used to scan the film, and save the image as a TIFF or PSD (not a JPEG) to preserve overall image quality.

Once you have scanned the film, you can optimize the resulting image to prepare it to be printed. In the context of Photoshop that would likely mean first adding a Black & White adjustment layer, and in Lightroom you could choose the “Black & White” option for the Treatment setting in the Basic section of adjustments. You’ll also of course want to optimize the overall image in overall tonality, detail, texture, and sharpness.

For the final print, you may also need to compensate for the capabilities of your printer. Many printers, for example, aren’t able to render full detail in the dark shadow areas. You can compensate by lightening up the value for the black point and darken down the value for the white point. This is something that would generally involve a degree of testing of your printer, so you know how much of a compensation to apply to produce a print with maximum detail.

It is also worth noting that in general you will want to use a custom printer profile, or custom software settings for your printer, to help ensure that the print is actually perfectly neutral. In many (or most) cases you will be using all of the ink colors in your printer to produce a black and white print, and it can sometimes be a challenge to produce a print that is perfectly neutral with only shades of gray, and without any hint of color cast.

Today’s Question: You’ve said a variety of things about the Adobe DNG [digital negative] file format, some good and some bad. But what I really want to know is, all things considered, should I convert my raw captures to DNG?

Tim’s Quick Answer: In a word, no. Taking all of the various factors into account, my personal preference (and general recommendation) would be to retain the original raw captures from your camera, and to not convert those original captures to the Adobe DNG format.

More Detail: Let me say right from the start that there are absolutely some great benefits to the use of the Adobe DNG file format compared to proprietary raw capture formats. I’m not suggesting that converting raw captures to DNG is somehow “bad”. I simply feel that on balance I’d rather retain the original raw capture format rather than converting those files to DNG and deleting the original captures. And I also don’t feel it makes a lot of sense to both convert to DNG and still retain your original raw captures.

One of the key reasons I prefer to retain the original raw captures is that they represent the original capture with no modification whatsoever. While the Adobe DNG format retains the pixel data from your original capture, there are some “private” metadata from the camera that may be lost. That information would generally relate to unique features of a specific camera model, which would require software from the camera manufacturer to fully leverage.

I also prefer to keep metadata updates separate from the original capture data. In the context of a raw capture that means, for example, having metadata updates written to an XMP “sidecar” so that the original capture file remains undisturbed. This can also help to streamline a backup workflow.

One of the primary motivations for using the Adobe DNG format is to avoid a proprietary file format that is not openly documented the way the DNG format is documented. In addition, DNG files are generally around 20% smaller than the original raw capture, with no loss of image quality or detail. So there are indeed advantages to the Adobe DNG file format, to the extent that if your camera supports capture directly to DNG, you may want to make use of that option.

But in the context of a workflow that might involve discarding the original raw capture file after converting to the Adobe DNG format, my preference is to simply retain the original capture files.