Bigger File but Less Data?

Facebooktwitterlinkedin

Today’s Question: You suggested that a TIFF image would not lose significant detail compared to a raw capture [in Friday’s Ask Tim Grey eNewsletter]. But wouldn’t the TIFF file actually have more data? Whenever I’ve created a TIFF from a raw capture the file is significantly larger.

Tim’s Quick Answer: A TIFF file will generally be about three times larger than a raw capture file because the TIFF includes full color information for all pixels. However, even though a raw capture does not include full color information for all pixels, that doesn’t mean the TIFF file would actually include more detail than a processed raw capture is capable of.

More Detail: Most digital cameras only record a single color value (typically either red, green, or blue) for each pixel in the image being captured. On a typical image sensor using the Bayer pattern, for every four pixels there would be one red value, two green values, and one blue value.

When the raw capture is processed to an actual image format, the “missing” information for each pixel is calculated. So, for example, a green and blue pixel value would be calculated for each red pixel, based on the surrounding pixel values. Since the raw therefore only contains one of the three primary color values for each pixel, the file size can be thought of as being one-third of what it normally would for a processed image.

An RGB TIFF image contains full color information for all pixels, so all other things being equal a TIFF file would be three times larger than the raw capture it was derived from. Of course, there are other factors that influence the actual file sizes, such as compression (lossless or lossy) that may be applied to either file format.

Just because the TIFF file is generally about three times larger does not mean it will contain more detail. In fact, depending on the processing and file settings applied to a TIFF image, there may be considerably less detail in a TIFF image compared to a raw capture that is processed with optimal settings.

The bottom line is that you can’t really evaluate potential detail contained within an image purely based on the size of the file. A variety of other factors will also impact the amount of visible detail in a given image file.

Data in Raw versus TIFF

Facebooktwitterlinkedin

Today’s Question: I’m wondering about the amount of data in an original RAW file vs that RAW file saved as a TIFF. I shoot Canon and all three of my current cameras have dust deletion as a menu option. It works really great but the problem is, it only works by using the Canon Digital Photo Professional (DPP) software. Once the dust deletion is applied the only options to save the file are JPEG and TIFF. My 1Dx Mark II is notorious for generating dust on the sensor. Even though the dust deletion adds an extra workflow step, it still saves time over removing hundreds of spots in Lightroom [Classic]. Any feel for what I may be losing by doing this spot removal in DPP and then continuing with “normal” processing in Lightroom?

Tim’s Quick Answer: I think it is perfectly reasonable to use Digital Photo Professional (DPP) for automatic dust removal, but I would also recommend applying at least basic overall tonal adjustments in DPP to help ensure the minimal amount of processing is required for the resulting TIFF image.

More Detail: The automatic dust removal feature available in certain models of Canon camera is indeed very impressive. You first need to capture a “Dust Delete Data” shot in the camera. While this process involves capturing a photo of a blank wall or sheet of paper, an actual photo isn’t captured. Rather, dust data is recorded by the camera, which is then appended to all raw (or JPEG) captures taken from that point forward.

The dust data is included in metadata, but requires the Canon Digital Photo Professional (DPP) software to process. So, you would need to use DPP to process the photos with the automatic dust removal feature. I also recommend applying basic tonal adjustments to get the overall image as close to final at this point, so less processing will be required later.

Save the final image from DPP as a TIFF image, and then import that TIFF into your Lightroom catalog. I would, for example, import the TIFF image into the same folder as the original raw capture you processed in DPP.

The point is that I would not be worried about significant loss of quality or detail in the image with this workflow. The TIFF image will be of very good image quality, with the benefit of dust spots having been removed automatically. You could then finalize the image in Lightroom Classic with any fine-tuning adjustments that are needed.

The TIFF from DPP will still be in the 16-bit per channel mode, so the file will still work very well if additional processing is necessary. You are losing a slight amount of flexibility in terms of processing the final image, but this is not something I would worry about in this context.

Bit Depth for Layer Masks

Facebooktwitterlinkedin

Today’s Question: Just read something today I’d never heard of and wondering if you have any input on this. I came across this searching for potential improved methods for hair masking. He states:

“…there’s a hard-wired inconsistency in Photoshop. Selections are always 8 bits. Once you load a 16-bit channel mask as a selection it becomes an 8-bit selection, and therefore virtually eliminating the 16 bits depth of the 16-bit masks.”

He did go on to say he’d not seen significant differences in the masks but I’ve come to trust you over the years and wonder if you had any thoughts.

Tim’s Quick Answer: Selections and layer masks in Adobe Photoshop are indeed 8-bit per channel even for 16-bit per channel images, but I don’t consider this to be of any concern at all. In other words, I don’t feel it will make any difference for a photographic image to attempt to create a mask in 16-bit that will only be converted to 8-bit per channel once the mask is used to apply a targeted adjustment to an image.

More Detail: The primary “risk” of working with your images in the 8-bit per channel mode is posterization, or the loss of smooth gradations of tone and color. For a typical color image in the 8-bit per channel mode, there are up to almost 16.8 million possible color values available. As a result, posterization is not a high risk unless you apply very strong adjustments to an image.

For black and white (grayscale) images the risk of working in 8-bit per channel mode is more significant. That is because an 8-bit black and white image can only have a maximum of 256 shades of gray, as compared to a maximum of 65,536 possible shades of gray for a 16-bit black and white image.

However, the concerns of posterization don’t really extend to layer masks. To begin with, very strong adjustments are generally necessary before any degree posterization will be visible in a color even at 8-bit per channel. If you’re working in 16-bit per channel mode for either black and white or especially a color image, the risk of posterization are not especially high. It would take very strong adjustments to create visible posterization, and I would suggest that an image requiring very strong adjustments in the first place probably wasn’t the best photo.

When it comes to layer masks (and by extension selections), the bit depth is not anywhere near as important. Even a somewhat posterized layer mask would still be mitigating the effect of even a strong adjustment across the image. It would require significant posterization on a layer mask combined with a rather strong adjustment being constrained by that layer mask in order to create any visible artifacts in the image.

Keep in mind that a somewhat typical layer mask might involve defining a “stencil” for the image that is divided between white and black, with some gradation between those areas to blend the targeted adjustment. Even with a more sophisticated layer mask, the fact that the mask only consists of up to 256 shades of gray would not lead to any concerns in terms of artifacts of other image quality issues.

So, I would say there is no benefit to creating the form of a layer mask in 16-bit per channel mode considering that mask will be converted to 8-bit per channel mode as soon as it is loaded as a selection or used as a layer mask in Photoshop.

Color Consistency with Hexadecimal?

Facebooktwitterlinkedin

Today’s Question: I use a specific color to add a watermark to my photos. I was told that if I use a hexadecimal value to choose my color, the color would be consistent whether I’m sharing my photos online or making a print. Is this true even if I’m using the sRGB color space for online images and the ProPhoto RGB color space for photos I’m printing?

Tim’s Quick Answer: No, a single hexadecimal (or RGB or HSL) color value will not produce the same color result for images with different color spaces. You would need to identify a specific color value for each color space in order to ensure the color will match across multiple color spaces.

More Detail: The color models used most frequently by photographers are device-dependent color models, meaning the actual color you will achieve with a given set of color values will vary depending on how the color is reproduced. For example, the RGB color model is used by many monitor displays, but each unique display might interpret individual color values in different ways. One of the key reasons for this type of variation is that the primary colors (such as red, green and blue for RGB) may be slightly different among different devices.

One of the side-effects of a device-dependent color model is that color values by themselves don’t actually represent a single specific color. You need a color profile to define what the color means. And for each different color profile, the same color values will generally produce at least slightly varied colors. So in order to ensure the same color across various output methods, you need to either use the same color space profile for all of that output, or you need to define the color values based on the specific profile being used.

There are two basic options you could use here. First, you could make sure to create the source image including your colored watermark as a “master” image, and then create derivative images from that single master. After creating a copy of the master image, for example, you could convert the copy to the sRGB color space and otherwise prepare that version for online sharing. You could then use the master as the basis for a print, using proper color management for the printing process. This would ensure the colors match as closely as possible for both types of output.

The other option would be to identify the appropriate hexadecimal (or RGB) color values for each color space you’ll use. Start with an image that includes the desired color in the correct color space, and of course note the color values for that color based on that color space. Then convert the image to the other color space you need to use (such as sRGB) and note the resulting (and different) color value for the color you’re using. You could then use those noted color values for different color spaces, setting the appropriate value based on the color space you are currently working in.

Note, by the way, that hexadecimal color values are really just a shorthand for RGB color values and are commonly used on the web for presenting colors online. You can essentially use hexadecimal or RGB values for colors interchangeably, keeping in mind that you must define a specific color space in order for those color values to have an accurate meaning in terms of the color you’re looking for.

You can learn more about color management in general with my course “Color Management for Photographers”, which you can get for half off if you use this link to get started:

https://timgrey.me/color

Delete from Collection

Facebooktwitterlinkedin

Today’s Question: I wanted to delete some photos, and rather than try to select them all I added them to the Quick Collection. But when I went to the Quick Collection, Lightroom Classic wouldn’t let me delete the photos. I could only remove them from the collection. Is there no way to delete photos that I’ve added to the Quick Collection?

Tim’s Quick Answer: You can delete photos from a collection in Lightroom Classic by first selecting all of the images in that collection, and then using the option to navigate to the source folder in order to delete the selected photos. Note, however, that this will only work if the photos are all in the same folder.

More Detail: When you choose the option to “remove” a photo from your Lightroom Classic catalog, the default action is to remove the photo from the catalog without deleting the source image file. However, if you are removing a photo from a folder, you have the option to delete the source images. Simply click the “Delete from Disk” button in the confirmation dialog after choosing the “Remove Photo” command. That command can be found on the Photo menu on the menu bar, or by right-clicking on an image.

However, if you are currently browsing a photo within a collection rather than a folder (including the collections such as the Quick Collection found in the Catalog section of the left panel in the Library module), you don’t have the option to delete the source image files. Rather, your only option is to remove the photo from the current collection.

To work around this, you can first navigate to the applicable collection, and then select the photo (or photos) you want to delete. If you’ll be deleting multiple photos, just be sure you only select photos that are contained in the same folder. Then, right-click on one of the selected photos and choose “Go to Folder in Library” from the popup menu. That will cause Lightroom to navigate to the folder where the selected image is stored, and the photos you selected will still be selected after switching from a collection view to a folder view.

At that point, having navigated to the folder and with the photo(s) still selected, you can right-click on one of the selected images and choose “Remove Photo” from the popup menu. In the confirmation dialog you can then click the “Delete from Disk” button and the photos will be removed from your Lightroom catalog and deleted from your hard drive. Note that the photos you delete will also automatically be removed from any collection they are contained in.

Reset Search Columns

Facebooktwitterlinkedin

Today’s Question: I often change the columns for the Metadata search category based on a specific need as far as locating an image. However, I then sometimes find it difficult to get all of the columns back to their starting point of Date, Camera, etc. Is there an easy way to reset these columns?

Tim’s Quick Answer: Yes, you can click the popup at the top-right of the Library Filter (to the left of the lock icon) and select “Default Columns” to quickly reset the columns to their default metadata options.

More Detail: The Library Filter bar provides a variety of options for filtering your photos, so you can track down a particular photo in many cases quite easily. Among the more powerful filter option is the Metadata tab. Within this tab you can select metadata fields for the various columns. For example, you could specify that you want to see photos from last year, captured with a particular lens, at a particular lens aperture and shutter speed.

It is also possible to add or remove columns to or from the filter criteria on the Metadata tab. The result is an ability to search for photos, potentially across your entire photographic catalog, based on whatever details you can remember about the metadata for the photo you’re looking for.

Of course, with so much flexibility, it is relatively easy to make a bit of a “mess” with the columns in the Metadata section of the Library Filter bar. In other words, you might want to simply reset the columns to their default value. And, as noted above, you can do exactly that. Simply click the popup to the left of the lock icon at the top-right of the Library Filter bar and choose “Default Columns” from the popup.

Color Temperature Seems Backwards

Facebooktwitterlinkedin

Today’s Question: Your answer about color temperature got me thinking about the settings on my camera. The manual says that Daylight has a temperature of 5200, and Shade has a temperature of 7000. But isn’t that backwards? Does the warmer light really have a cooler temperature?

Tim’s Quick Answer: The temperature settings on your camera aren’t backwards. The Kelvin scale is basically the opposite of the “psychological” values of warm and cool that we use to describe the color of light. So the “Shade” setting compensates for a Kelvin temperature of 7000, which is relatively blue. The result is an image that is shifted toward yellow, so that the image appears less blue.

More Detail: As photographers when we talk about warm lighting (or color) for a photo, we are referring to colors in the range of red, orange, and yellow. When we talk about cool lighting (or color) we are talking about colors such as cyan and blue. But this is actually the opposite of the Kelvin color temperature scale.

On the Kelvin scale, the colors we describe as “warm” have a lower temperature, and the colors we describe as “cool” have a higher temperature. That is because the Kelvin scale relates to science, not to the psychological attributes we have assigned to colors.

The Kelvin scale is based on the concept of a theoretical black body radiator. This refers to the color of light an object will give off as it is heated up. Initially that object will glow red, but as it gets hotter and hotter it will transition through yellow, and then on to blue.

On your digital camera, the white balance presets refer to the color of light they are compensating for. The illumination provided by sunlight in a shady area appears rather blue, which has a moderately high Kelvin value (at least in the contest of visible light). To compensate for light with a color appearance around 7000 Kelvin, you need to shift the color toward yellow.

This issue can also be a little confusing in software applications such as Lightroom Classic. When you adjust the Temp slider to a higher temperature value, the color in the image does indeed “warm up”. But that is because you are compensating for a light source that is more blue, with a higher Kelvin temperature. So, the color in the image is actually getting shifted to a lower Kelvin temperature, but we would describe the image as having a warmer appearance.

I realize all of this can be a bit confusing, and perhaps a bit technical. But I do think it can be helpful to understand the basis of the numbers we’re using to optimize the appearance of our photos, both at the time of capture and in post-processing.

Temperature Scale Confusion

Facebooktwitterlinkedin

Today’s Question: While I don’t totally understand the numbers, I’m accustomed to the white balance adjustment in Lightroom Classic showing a temperature value of somewhere around 5,000 (sometimes considerably lower, sometimes a bit higher). However, with some images the value for the temperature is zero (until I apply an adjustment). I can’t figure out why some images have a range I’m expecting, and others have a zero value to start with. Any ideas?

Tim’s Quick Answer: The “normal” temperature scale you’re referring to is shown for raw captures. For other supported image formats such as JPEG or HEIC photos, the scale is an adjustment with a default value of zero.

More Detail: For most supported image formats in Lightroom Classic the Color Temperature (Temp) and Tint sliders operate in much the same way as many of the other adjustment sliders. For the Temp slider, that means the default for images such as JPEG and HEIC captures is a value of zero, with the ability to shift toward blue with a minimum value of -100, or toward yellow with a maximum value of +100.

For raw captures, the Temp adjustment represents color temperature values in degrees Kelvin. The actual value represents the number of degrees Kelvin representing the color of the light being compensated for. For example, if the illumination of the scene was a rather blue light, the value for Temp would be relatively high, indicating the temperature of the light being compensated for. That would result in a shift toward a more yellow (or at least less blue) appearance.

For all image types (including raw captures) the Tint slider functions mostly the same. You can shift toward green with a minimum value of -150 for raw captures and -100 for other image formats. When adjusting toward magenta the maximum value is +150 for raw captures and +100 for other image formats. The only other difference among image types is that for raw captures the default value for Tint will be based on the in-camera white balance setting. For all other image types the default value is zero.

The point is that the key difference in the scale for the Temp slider relates to raw captures versus other standard image types. But the overall function of the Temp and Tint sliders is essentially the same in terms of actually adjusting color for a photo.

Manual Focus with Progressive Lenses

Facebooktwitterlinkedin

Today’s Question: Regarding manual focus: You reference using the live view to focus when wearing glasses, but any hints for those of us who wear progressive lenses? I’m never sure what part of the glasses lens I’m looking through, so the focus is often not very sharp. Should I just get tri-focal lenses for photography?

Tim’s Quick Answer: Depending on your vision prescription, you may be able to avoid glasses altogether when photographing by adjusting the diopter on your camera’s viewfinder (if it is so equipped). You could also opt for eyeglasses that do not have progressive lenses when you are photographing.

More Detail: I too have eyeglasses with progressive lenses and find it difficult to make sure I’m looking through the right portion of the lenses when evaluating sharpness. When using the LCD in Live View mode, I can use the text on the display to help make sure I’m looking through the right portion of the glasses. If the text looks sharp, then I’m looking through the right portion to evaluate the rest of the image preview.

If you prefer to use the viewfinder, a diopter adjustment may provide a solution. If your camera has a diopter, you can apply an adjustment so the view is in focus when you aren’t wearing your glasses. As long as your vision prescription isn’t too strong, this can provide a good solution.

Another option might be to use reading glasses with a single correction factor (not progressive lenses) when photographing, assuming that is an option for you based on your prescription. This would enable you to have a single vision correction that would be suitable for evaluating focus based on the camera’s LCD display.

Trifocal (or even bifocal) lenses would be a good idea if the above didn’t work, since the lack of blending for the focus zones on the lenses would make it easier to know when you’re looking through the correct portion of the lens. This would make it possible, for example, to use one portion of the lens for evaluating focus on the camera’s LCD display, and another portion for evaluating distant focus through the viewfinder.

Storage Upgrade Workflow

Facebooktwitterlinkedin

Today’s Question: I wish to add and consolidate significant storage (new drives) to my Lightroom [Classic] catalog of folders and files. I have several hard drives that I want to consolidate into a pair of 6TB drives, including images and backups. The question is: Can this be done efficiently through the Lightroom folders panel? Or, should I do it with an external application like ChronoSync, and then reconfigure the Lightroom links?

Tim’s Quick Answer: The transfer and consolidation of your photo storage should be done within Lightroom Classic. The backup of the photo storage needs to be performed outside of Lightroom through the use of third-party software.

More Detail: Attempting to move and consolidate storage outside of Lightroom Classic and then reconnect the folders and photos that would then be in a different location than Lightroom expects them would be a daunting task. Instead, the transfer of your photos to a new storage device should be done within Lightroom Classic.

Before doing anything, I recommend backing up all of your photos and your Lightroom catalog, just to be on the safe side. Then you can start the process of migrating your storage.

After configuring the new hard drive for use (such as formatting it if necessary) you can add a folder to that drive from within Lightroom Classic so the drive will be visible within Lightroom. To create that new folder, click the plus symbol (+) to the right of the Folders heading on the left panel in the Library module and choose “Add Folder” from the popup menu. Navigate to the new hard drive, and click the New Folder button at the bottom-left of the dialog. Give the folder a name (such as “Photos”) and click the Create button, then click the Choose button.

At this point you will see the new folder under a heading for the new hard drive. You can then drag-and-drop folders from the previous storage location to the new storage location. I recommend doing this in relatively small batches, to make it easier to recover if there are any errors along the way.

After you’ve moved all of the photos and folders to the new consolidated storage, you’ll want to create a backup of the new hard drive. ChronoSync is one tool that makes it easy to backup an entire hard drive. I use a similar software tool called GoodSync, which you can learn more about here:

http://timgrey.me/greybackup