What is “Demosaicing”?

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Today’s Question: In a recent Ask Tim Grey eNewsletter you made reference to the “demosaicing” of a raw capture. What exactly is “demosaicing”?

Tim’s Quick Answer: The term “demosaicing” refers to the process of calculating the “missing” color values for each pixel in a raw capture, due to the fact that most raw captures only record a single color value for each pixel in an image.

More Detail: When you capture in raw mode on most digital cameras, the sensor is only recording a single color value for each pixel. For example, many digital cameras use a sensor that employ the “Bayer pattern” for the color values. In this configuration, for each four pixel values there will be two pixels that record only the green color value, along with one pixel recording the red value and one pixel recording the blue value.

The lack of full RGB color information for each pixel is a product of the image sensor in the camera, not the raw capture format. For photos captured with an actual image format, such as JPEG, the data gathered by the image sensor still only represents one out of the three required color values for each pixel. The difference is that with a JPEG capture, for example, the camera calculates the “missing” values for each pixel. With a raw capture, the “missing” color values are not calculated at the time of capture.

Therefore, with a raw capture, part of the process of rendering the raw capture into an actual image file is calculating the “missing” color values for each pixel. That process is referred to as “demosaicing”.

It may be hard to believe that software could “magically” calculate two-thirds of the “missing” data for a given pixel. However, when you consider the context for these calculations, it is I think much easier to understand. Let’s consider the green channel, for which half the pixels have information that was gathered by the image sensor and half the pixels have no information.

If you imagine a black and white photo where half of the pixels are missing, I think it isn’t all that difficult to imagine that software could figure out appropriate values for the “missing” pixels somewhat easily. Even for the red and blue channels where three-quarters of the pixels are missing, you can probably appreciate that software could calculate the values for the missing pixels based on the context of those pixels that do exist, again without too much difficulty.

This is the actual process behind the scenes with demosaicing. And considering we’ve all been happy with the photographic results we’re able to achieve with raw captures, obviously the process of demosaicing actually works in the real world.

Whether or Not to Watermark

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Today’s Question: I’ve heard pros and cons on adding watermarks. What are your thoughts?

Tim’s Quick Answer: Adding a watermark when sharing your photos is a good way to help promote your brand as a photographer, and can also help discourage the theft of your images. However, especially if the watermark is not exactly subtle, that watermark can interfere to some extent with the viewer’s experience of enjoying your photos.

More Detail: The watermarking of photos shared online is a perhaps surprisingly controversial subject. I have been criticized by a number of photographers when I mention that I don’t generally watermark my photos when sharing them online, as though I am somehow advocating for the unauthorized use of photos when sharing them without a watermark.

To be sure, I don’t like it when I discover that someone has made use of my copyrighted content without paying me for that content. But the only way to prevent anyone from being able to steal your content is to never share that content in any form. If you share a photo online, it is always possible to steal that photo. And even if you watermark the photo, it is generally possible to remove that watermark through the magic of software such as Adobe Photoshop.

My personal feeling is that the benefit of sharing my photos exceeds the risk involved with someone potentially stealing my photos. When I share a photo there is a chance that someone might want to buy a print of that photo, hire me as a photographer, or join me on a photo workshop. That potential value is, to me, worth the risk that someone might steal my images.

That said, a watermark can also help to promote your brand as a photographer. Therefore, if you are trying to market your photography services, I think it makes perfect sense to include a modest watermark that promotes your brand or website as a photographer.

As an aside, I will admit that I find it rather amusing that I often hear photographers complain about scenarios where their photos might be stolen online, when I’ve also seen a large number of photographers present slideshows of their photos accompanied by popular music that I suspect they have not paid a licensing fee to include as part of their slideshow.

Format for Master Image

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Today’s Question: Regarding, RAW and TIFF, once I process a RAW file, what is the best format to save it that will preserve all of the info captured by shooting in RAW? Is it TIFF along with its three times larger file size? I can’t imagine that one should save to JPEG, which would defeat the advantages of shooting in RAW.

Tim’s Quick Answer: The best answer depends to some extent on which software you’re using to manage your photos. That said, if you’ll be saving a “master” image from a processed raw capture, I recommend saving in the TIFF file format. The Photoshop PSD is also a good choice for this purpose, while the JPEG format is a bad choice.

More Detail: If you are using Adobe Lightroom to manage your workflow, there’s no need to save a new “master” image based on your original raw capture, because you don’t actually need to save a new file. Lightroom employs a non-destructive workflow whereby the adjustments you apply are essentially just metadata updates that relate to a specific raw file. You only need to create a new file when you want a copy of the image for purposes of sharing, such as to post online or send to a service provider to be printed.

If, on the other hand, you’re using software such as Adobe Photoshop to optimize your photos, you’ll need to save the processed version in a specific file format. Perhaps the worst choice for saving this new “master” image would be the JPEG file format. That is because the JPEG file format always involves “lossy” compression that will reduce overall image quality and likely cause visible artifacts, the resulting image won’t be capable of preserving any layers you created in Photoshop, and the file can only be saved with an 8-bit per channel bit depth.

To maximize the image quality and amount of detail in a master image you save based on processing a raw capture, I recommend using the TIFF file format. You can save such a file without lossy compression, in the 16-bit per channel bit depth, and with layers from Photoshop included. Similarly, the Photoshop PSD file format works perfectly fine, though in many cases you can achieve a smaller file size using the TIFF file format.

It is true that the TIFF (or PSD) file will be approximately three times the file size of the original raw capture, depending on the number of layers, compression applied, and other factors. However, if you need to create a derivative copy of the original raw capture as a new “master” image, in my view that file size is well worth the storage requirements in order to ensure optimal image quality.

Which Adjustments Where?

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Today’s Question: I am working my way through your Photoshop training. Many of the adjustments you discuss in Photoshop are also available in Lightroom [Classic] and Adobe Camera Raw. I’m thinking of the graduated filter versus the gradient tool, HSL [Hue, Saturation, and Lightness], Curves, etc. I realize that most of the adjustments in Photoshop are done using adjustment layers which are non-destructive unless flattened but those in Lightroom are also non-destructive. Is there anything inherently better about saving such adjustments for Photoshop versus utilizing Photoshop only for tasks not available in the raw editors?

Tim’s Quick Answer: While it is generally best to perform as many of your adjustments as possible with the original raw capture rather than later in your workflow, my preference is to save most targeted adjustments and image cleanup work for Photoshop, using Lightroom Classic (or Adobe Camera Raw) for all other adjustments.

More Detail: There is a theoretical benefit to applying as many adjustments during the raw-conversion process as possible. However, it is worth keeping in mind that many of the adjustments you might be applying with your raw-processing software are actually applied after the “demosaicing” process. In other words, many of the adjustments are applied after the raw capture has been converted to actual pixel values.

The result is that for the most part I make a decision about which adjustments to apply at which stage of my workflow from the standpoint of both image quality and workflow convenience.

I recommend applying most adjustments in Lightroom Classic or Adobe Camera Raw, rather than saving those adjustments for Photoshop. Instead, I only save adjustments for Photoshop when I have a good reason to do so.

I save most image cleanup work for Photoshop rather than Lightroom or Camera Raw because the cleanup tools in Photoshop are more powerful and effective. This includes, for example, the Content-Aware technology being available for several of the image cleanup tools in Photoshop. For very minor dust spots in easy to clean areas, I’ll use Lightroom Classic for cleanup. But for anything beyond that, I perform the cleanup in Photoshop.

I also save most targeted adjustments for Photoshop, primarily because the tools and features for selections and layer masks provide a greater degree of control compared to what is available in Lightroom or Camera Raw. This enables you to apply targeted adjustments with a much higher degree of precision in Photoshop.

There are also a variety of creative filters and other effects you can apply in Photoshop, which are not available in Lightroom Classic. Those are obviously options I would take advantage of in Photoshop when I want to apply such an effect.

Catalina Upgrade Concerns

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Today’s Question: I have held off on upgrading to [MacOS] Catalina out of concern for how it might affect Lightroom [Classic]. Am I worrying about nothing?

Tim’s Quick Answer: At this point I would say it is perfectly safe to upgrade to MacOS Catalina, though your worries are understandable since there were more than a few significant problems with this update when it was initially launched.

More Detail: One of the side effects of my work is that I often need to install software updates early, sometimes before they are even released to the general public. This enables me to learn about the updates quickly so I can be ready to help educate photographers about those updates and help them troubleshoot problems should they arise.

The update to MacOS Catalina was my most painful operating system in recent memory. A variety of software applications and device drivers did not function properly, in some cases because the software applications hadn’t been updated and in part due to bugs and compatibility issues. There were also a variety of operating system or related features that were not working properly, crashing, or experiencing other problems.

I upgraded to MacOS Catalina as soon as it was officially released in early October 2019. I almost immediately regretted performing that upgrade from the standpoint of running into a number of problems with the update. Over time, with additional updates to the operating system and other applications, things started to stabilize. Within a couple months of the initial release, I was back to completely normal functionality with MacOS Catalina.

In the last few months I have not experienced any issues with the latest update to Catalina. Everything is stable with all features working properly, and all applications that I use also working without any issues.

I should also note that there are a variety of new features and other improvements in MacOS Catalina that I feel make the update worthwhile. But of course, the most important first requirement is that your system and software applications will be fully functional when you upgrade, and at this point my feeling is that there is no reason to postpone this update.

Capture Sharpening Settings

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Today’s Question: In Thursday’s Ask Tim Grey eNewsletter you said that sharpening should always be applied in the Develop module of Lightroom Classic. The sharpening adjustment is set at Amount 40, Radius 1.0 and Detail 25. I guess this is the default. So, would you go beyond that and increase the Amount or other factors?

Tim’s Quick Answer: Those settings are the defaults for raw captures in Lightroom (as well as Adobe Camera Raw), and are reasonably safe settings for most images. However, I do recommend reviewing (and refining) these sharpening settings for images you are optimizing for eventual sharing.

More Detail: Sharpening is applied by default in Lightroom Classic (as well as Adobe Camera Raw) to all raw captures. For other image formats, such as JPEG captures, there is no sharpening applied. The lack of sharpening for other formats is generally a good thing, as there is a good chance that a JPEG capture, for example, will have had some degree of sharpening applied in the camera at the time of capture.

For raw captures in particular, I highly recommend evaluating the settings for sharpening, and refining them to optimize the appearance of the photo. Very generally this would involve possibly reducing the value for Radius by at least a small amount, and increasing the value for Amount. You might also want to fine-tune the Detail and Masking values depending on the image.

For images with a fair amount of relatively fine detail, I generally set the Radius to a value of about 0.6 to 1.0, which means I often reduce the setting at least slightly. When the texture has a bit larger structure in the image, with smoother transitions along contrast edges, I’ll often increase the Radius setting to somewhere between about 1.0 and 2.0.

For images where I want to make sure the fine detail is enhanced, I typically increase the value for Amount to somewhere between 50 and 75. It is important not to take this setting too far, creating what amounts to the appearance of noise or over-sharpening halos in the image. The lower the setting for Radius, the higher you can push the value for Amount. And the higher the setting for Radius, the more careful you need to be about increasing the value for Amount.

You can increase the value for Detail if you want to be sure to emphasize as much fine detail as possible, and reduce the value if you don’t want to accentuate details too much. A high value can sometimes result in a somewhat “crunchy” appearance of too much texture in the photo.

Finally, you can increase the value for Masking to focus the sharpening effect only on areas with a fair amount of texture, helping to protect smooth areas of the image from getting sharpened. When you apply sharpening to relatively smooth areas of a photo, those areas can appear to have a bit too much noise or texture.

For all of these settings you can hold the Alt key on Windows or the Option key on Macintosh while dragging the slider to get a grayscale preview that shows more clearly how the setting is impacting the photo. And, as always, I recommend evaluating the effect of sharpening at a 1:1 (100%) view setting.

Sharpening Strategy

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Today’s Question: I now shoot with a mirrorless camera. Adobe Lightroom Classic has sharpening in the develop module that I used for “capture” sharpening when I used to shoot with a Nikon DSLR. Should I just use that sharpening when I am going to do something with my photo like share it online or print, once I know how the photo will be used? If so can I just use the sharpening in Lightroom’s export feature? Will I ever need to use the various approaches to sharpening in Photoshop 2020?

Tim’s Quick Answer: The sharpening in the Develop module should be applied to every single capture, regardless of the type of camera that was used. Additional sharpening should generally be applied for images that are being prepared for output, with that sharpening based on the specific details of how the image will be shared.

More Detail: The sharpening found in the Develop module in Lightroom Classic, or in Adobe Camera Raw for Photoshop users, is generally referred to as “capture” or “input” sharpening. That is because this sharpening is intended to compensate for factors that lead to a loss of sharpness in the capture. Based on this, I recommend that this sharpening be applied modestly to all images, regardless of how you will share those images.

When you’re ready to share a photo, you’ll generally want to apply an additional step of sharpening that is optimized for the final output. That means applying this sharpening based on the final output size, as well as the medium through which the image will be shared. For example, when printing (especially to uncoated matte papers) you need to over-sharpen the image to some extent, in order to compensate for the softness caused by the spreading of ink on the paper.

For online or other digital sharing you will generally need only a modest amount of additional sharpening, in part to compensate for a loss of detail from reducing the overall resolution of the image, and in part to help the image look its best.

When exporting an image from Lightroom Classic, you have the option of applying sharpening. However, there isn’t much control (or a preview) available for this sharpening. For basic digital or online sharing, I’m comfortable using this output sharpening. But for printing I prefer to send the image to Photoshop and make use of the Smart Sharpen filter. Just be sure that when sharpening “manually” in Photoshop that you are applying sharpening as the final step, after the image has been resized for the final output.

Display Calibration Update

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Today’s Question: Wanting to calibrate my mac 27” monitor, I reviewed three of your Ask Tim Grey letters from mid-July 2019. You recommended X-Rite ColorMunki Smile. However, per X-Rite the Smile only works with 32-bit and I believe my Catalina macOS version is 64-bit system. What do you recommend?

Tim’s Quick Answer: You will need to opt for a different solution, and I recommend the X-Rite i1Display Studio, which you can find here:

https://timgrey.me/calibrate

More Detail: With the update to MacOS Catalina, applications essentially must be 64-bit rather than 32-bit. Many software applications have of course been updated so they can be run on the latest version of the operating system, but not all applications have.

The monitor calibration software included with the X-Rite ColorMunki Smile colorimeter has not been updated to 64-bit, and X-Rite has indicated they will not be developing an update. In other words, you can’t use the ColorMunki Smile display calibration package on a computer running MacOS Catalina.

The X-Rite i1Display Studio package is the “next step” up the line of products from X-Rite, and so is the option I would recommend as an alternative to the X-Rite ColorMunki Smile. You can find the i1Display Studio package here:

https://timgrey.me/studio

The software included with the i1Display Studio already supports MacOS Catalina, so you’ll be able to calibrate your display on the latest version of this operating system.

Cleanup and a New Computer

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Today’s Question: I just started your course, “Cleaning Up Your Mess in Lightroom” [Classic]. I bought a new Mac that I’d like to start using for Lightroom. Should I clean up my Lightroom mess on my old Mac first, before migrating to a new Mac? Also, do you have instructions on how to move Lightroom from one Mac to another? I am using external drives to store my photos and Lightroom catalog.

Tim’s Quick Answer: Since you have your photos and Lightroom Classic catalog stored on external hard drives, you can migrate directly to your new computer. After installing the latest version of Lightroom Classic on your new computer, you can connect the external drives and open your catalog to get started.

More Detail: Normally I might recommend getting things cleaned up with your existing configuration before making the move to a new computer. The idea is to try to avoid changes that might lead to confusion and new problems until after cleaning up your Lightroom Classic catalog.

In this case, however, since your photos and Lightroom catalog are already on external hard drives, the transition can be made quite easily. The first step, of course, is to get Lightroom Classic installed on the new computer. Then you can connect your external hard drives to the new computer, and open your Lightroom Classic catalog from the external hard drive.

For Macintosh users, at this point everything will be working normally in Lightroom Classic just as it had been on your old computer. For Windows users, however, there may be an additional step. That’s because on Windows the drive letter designations for hard drives are not always maintained when you switch computers or even connect drives in a different order.

On Macintosh the volume label is used, which is basically the name for the drive. That won’t change when connecting to a different computer, so Lightroom won’t be confused. For Windows users, if the drive letters for the external hard drives don’t get assigned with the same drive letters from the old computer, you would need to go into Disk Management and assign the drive letters used on the old computer to the drives when attached to the new computer.

Note that if you also have a mess to clean up in Lightroom, you can get a 50% discount of my “Cleaning Up Your Mess in Lightroom Classic” course if you use this link to get started:

https://timgrey.me/mess20

Automatically Remove People

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Today’s Question: I have seen a way to take moving objects out of a group of photos. For example, take 10 anchored (tripod) photos over a 5-minute period (every 30 seconds), then open them up in Photoshop and you can ‘merge’ so only the static objects in the photos appear. Any cars or people that move around are removed. How do we do that?

Tim’s Quick Answer: You can automatically remove people and other moving objects in a scene captured with multiple photographs by loading the source images into a stack in Adobe Photoshop and then using a special blending mode that blends a final image by retaining only pixels that match among multiple images.

More Detail: To create this seemingly magical effect, you obviously first need to capture multiple images of a scene from a stable platform such as a tripod. You want to capture enough images that for any given area of the photo, there is at least one image that shows that area clear of moving subjects such as people or cars.

You can then open all of the captures into Photoshop so they are available for processing. Then go to the menu and choose File > Scripts > Load Files into Stack. In the “Load Layers” dialog that appears click the “Add Open Files” button, and the images you opened will appear on the list under the “Use” heading.

Within the Load Layers dialog turn on the “Attempt to Automatically Align Source Images” checkbox as well as the “Create Smart Object after Loading Layers” checkbox, both of which are found at the bottom-left of the dialog. Then click OK to have the images combined into a single image consisting of a Smart Object that contains the source images.

To complete the effect go back to the menu and choose Layer > Smart Objects > Stack Mode > Median. This is the real magic of the effect, and will cause the multiple images to be blended in such a way that anything that had been moving within the scene from one capture to the next will be removed, leaving an empty scene in your final image.