Ask Tim Grey

Today’s Question: You said “especially uncoated matte papers” [in a recent Ask Tim Grey eNewsletter on the topic of sharpening a photo for printing]. I thought all matte papers would be uncoated. Can you explain the differences?

Tim’s Quick Answer: Some matte papers do indeed include a special coating that provides a matte surface that takes on some of the behaviors of a glossy photo paper.

More Detail: While glossy papers have an obvious coating that enables the inks to “sit on top” of the paper, many matte papers also have a coating. The only difference is that the coating used on matte papers isn’t as “shiny”, so that the paper retains a matte appearance. The benefit of that coating can be tremendous in terms of the amount of saturation, detail, and even dynamic range you’re able to achieve with these matte papers.

The key challenge for an uncoated matte paper is that the inks get absorbed somewhat significantly by the paper. The result is a relatively dull appearance, with reduced contrast, reduced saturation, and lower dynamic range. By using special coatings with a mate paper surface, the inks will stay closer to the paper surface and will spread out less, helping achieve a result that is closer to what you would expect on a glossy (or semi-gloss paper) without the shiny appearance.

In some cases you may prefer the look of an uncoated matte paper, but I generally find that I prefer coated matte papers since they provide some of the benefits of a glossy surface while maintaining the aesthetic appeal of a matte paper.

Today’s Question: Does this technique make sense? “Placing a blank, white layer atop a .PSD can cut the file size in half?”

Tim’s Quick Answer: No, not really. This “trick” may have worked in older versions of Photoshop (or the person who tested it wasn’t being very methodical), but I’ve not been able to reproduce the effect in recent versions of Photoshop. But regardless, the real issue here (from what I can gather) is the “Maximize Compatibility” setting in Preferences, which when enabled will approximately double the base file size for PSD images.

More Detail: When I read about this technique, I immediately suspected the underlying issue related to the Maximize Compatibility option. Specifically, the white layer atop the stack of layers on the Layers panel would cause the preview for the image to be entirely white, which would result in a preview that compresses better and thus produces a smaller overall file size.

However, that approach would completely defeat the whole purpose of having the Maximize Compatibility feature turned on in the first place. The reason the Maximize Compatibility option causes the file size to double (compared to a flattened original image) is that this option causes a full-resolution composite preview of the image to be embedded. This allows other applications to see the actual appearance of the image without having to understand the various underlying layers that are specific to Photoshop.

However, rather than using this “trick”, you can simply turn off the Maximize Compatibility option in the first place. That way, rather than having a blank white preview you will have no preview at all, causing the file size to be approximately half of what it otherwise would have been with Maximize Compatibility turned on.

Keep in mind, however, that by turning off Maximize Compatibility for the PSD files you save, you won’t be able to see previews of those images with other applications that might otherwise be able to show a preview. You also won’t be able to import PSD files into Lightroom if Maximize Compatibility is turned off.

You can choose whether you want the Maximize Compatibility option enabled in the File Handling section of the Preferences dialog in Photoshop. I generally leave the option set to “Ask” so I can choose whether to enable Maximize Compatibility based on how I’ll be using the PSD file.

Today’s Question: What is the difference in effect on my image between making an adjustment in Camera Raw while in Bridge versus making the same adjustment with the Camera Raw filter after the image file is in Photoshop?  Is the adjustment better done in Bridge?

Tim’s Quick Answer: The basic effect applied to the images is the same whether you’re using Adobe Camera Raw to process an image or the Camera Raw filter in Photoshop. The key difference is that when processing a RAW capture in Adobe Camera Raw, you are taking advantage of the benefits of some of the adjustments being applied as part of the RAW conversion process. In other words, in both cases you are applying the same adjustments, but you are applying them to different data.

More Detail: As you may be aware, when you capture a RAW image the source file only contains one value for each pixel. In other words, for each pixel in the capture, only a red, green, or blue value is recorded (with some exceptions). The process of “filling in the gaps” is referred to as demosaicing, and there are benefits to including adjustments as part of this process in terms of retaining detail and improving quality.

Therefore, I highly recommend applying at least basic tonal and color adjustments during the conversion of the RAW capture, to ensure the best starting point for your image. In many respects I think it is reasonable to compare the RAW conversion process to the original capture. Just as you want to ensure the best initial capture, being careful to produce a good result from a RAW conversion can have a big impact on the final image.

The Camera Raw filter in Photoshop simply provides the same basic adjustments found in Adobe Camera Raw for images that have already been processed from a RAW capture to actual pixel values. You can therefore use the Camera Raw filter at any time while working on your photo to apply adjustments if you are more comfortable with the options available in Camera Raw compared to the other adjustment options found in Photoshop.

Today’s Question: Can you provide some guidance for the Smart Sharpen settings in Photoshop when preparing an image for printing?

Tim’s Quick Answer: The first thing I recommend when using the Smart Sharpen filter is to set the Remove option to “Lens Blur”. The Reduce Noise setting will depend, of course, on the degree of noise in the image, but generally a low setting can be used because you will have presumably applied noise reduction to the image already. Then, for high detail images set the Radius to a value somewhere around 1.0 pixels (generally a little lower, except for very large prints). For images with lower levels of detail and smoother transitions of that detail, use a higher setting for Radius, generally around 2.0 to 3.0 pixels. Then set the Amount to a value of around 150% or so (ranging between around 100% and 200%) for high detail images, and around 75% for lower detail images. The specific settings will, of course, vary a bit based on the print size and the degree of detail in the image.

More Detail: When printing, the key thing to keep in mind is that you’ll generally need to over-sharpen the image. For glossy paper you don’t need to over-sharpen too much, but for matte papers (especially uncoated matte papers) you may have to apply sharpening that seems slightly extreme in order to produce a good result in the print.

It can take a bit of practice to get accustomed to what an image should look like on your computer display to ensure a print with optimal sharpening. Practice can be very helpful in this regard.

For high-detail images you want the sharpening effect to be applied to relatively small areas in relation to the size of the transitions among detail in the image. For lower-detail images you need to compensate by using a higher setting for Radius, so the sharpening effect will spread out a bit more.

When using a relatively low setting for Radius, you need to use a relatively high setting for Amount. And when you are using a relatively high setting for Radius you need to use a relatively low setting for Amount.

It is worth noting that you can also mitigate the sharpening effect in the dark shadow or bright highlight areas of a photo by expending the Shadows/Highlights section. This will provide independent controls for the Shadows and Highlights. You can then use the Fade Amount slider to reduce the application of sharpening in the shadows or highlights. You can also expand the range of tonal values being affected by this mitigation using the Tonal Width slider. Finally, you can use the Radius setting for Shadows and Highlights to determine how large an area around each pixel will be evaluated for purposes of determining whether that area represents a highlight or shadow area.

Today’s Question: A friend recently told me he was using Lightroom 5 with smart previews and Dropbox to synchronize his Lightroom catalogue. That is, he put his catalogue in Dropbox, set up smart previews in Lightroom and was able to work on his laptop and have it all synced to his main computer where all the original images were stored. I think i understand the concept but was curious about your take on the subject.

Tim’s Quick Answer: This absolutely works, but it does make me a little nervous. In concept, provided you have an adequately fast Internet connection (or aren’t generally in a tremendous hurry), you can synchronize your Lightroom catalog via Dropbox (or a similar service) and access your Lightroom catalog across multiple computers. In fairness, I’ve never experienced any problems when synchronizing a Lightroom catalog via Dropbox, and I’ve never heard of photographers having any serious problems. But it does make me nervous to take this approach.

Tim’s Quick Answer: This absolutely works, but it does make me a little nervous. In concept, provided you have an adequately fast Internet connection (or aren’t generally in a tremendous hurry), you can synchronize your Lightroom catalog via Dropbox (or a similar service) and access your Lightroom catalog across multiple computers. In fairness, I’ve never experienced any problems when synchronizing a Lightroom catalog via Dropbox, and I’ve never heard of photographers having any serious problems. But it does make me nervous to take this approach.

More Detail: When you access a Lightroom catalog (or other files) “remotely” using Dropbox (or a similar service), you aren’t actually working directly with the files on an Internet-connected server. What’s actually happening is that you are accessing the files locally on your computer, but those files are being synchronized via Dropbox.

So, for example, you could place your Lightroom catalog files in your Dropbox folder, and then access those files via several different computers. But when you do so, the files are actually copied to each of those computers. So you’re actually accessing the files locally, but they are being synchronized across multiple computers via Dropbox.

The biggest challenge here is that the files related to your Lightroom catalog can get rather large, especially the preview files. This can cause the synchronization to be rather slow, depending on the speed of your Internet connection. The key thing to remember here is that if you have updated your Lightroom catalog on one computer, you can’t make updates on another computer until the synchronization is completed. In theory the service (such as Dropbox) that is performing the synchronization won’t let you update a file (such as your Lightroom catalog) until the synchronization for that file is complete. But trusting this limitation makes me nervous, and waiting for the synchronization to complete could involve considerable time with a large set of catalog files on a slow Internet connection.

So, again, this is perfectly feasible, but potentially problematic. I’ve performed considerable testing using Dropbox to synchronize a Lightroom catalog across multiple computers without any difficulty, but I don’t feel comfortable enough with this solution (especially considering potential latency based on the Internet connection) that I’m willing to use this approach with my “real” Lightroom catalog.

Today’s Question: Upon reviewing a group of recently imported images into Lightroom 5, I noticed strong alternating blue and yellow bands across textured metal surfaces in 3 of my photos. Lightroom automatically removed the banding in 2 of the images within a few seconds of switching to the Develop Module. However, the third and most strongly banded image, containing a bank of escalator steps, remains unaffected. Any suggestions?

Tim’s Quick Answer: Your description certainly sounds like chromatic aberration. Presumably you have the “Remove Chromatic Aberration” checkbox turned on with your default settings in the Lens Corrections section of the right panel in Lightroom’s Develop module. However, this option doesn’t always provide a complete solution. You can, however, make use of the Defringe options below the “Remove Chromatic Aberration” checkbox on the Color tab of the Lens Corrections section to further improve the result.

More Detail: The type of visible artifacts you describe can be caused by a variety of factors, and fortunately can be resolved very effectively with the Lens Corrections adjustments available in Lightroom’s Develop module as well as Adobe Camera Raw, among a variety of other software tools that provide this correction option.

I find that in about half of the images that require a correction for this type of color fringing, the “Remove Chromatic Aberration” checkbox provides a good solution. In the other half of images that require this correction the Defringe controls provide enough control to resolve the color fringing.

There are two sets of controls for Defringe, allowing you to adjust the Amount (strength) of the correction and the range of color values to be corrected. The first set of sliders applies to magenta fringing in the image, and the second set applies to green fringing.

My approach for the Defringe sliders starts by zooming in on the area of the image where the color fringing is visible. Then increase the Amount slider significantly for the color correction that is needed (or the color that is closest to the problem color) to see if the fringing is corrected. If the color fringing is not completely removed with a large increase in the Amount control, you can expand the color range for the applicable Hue slider. Be careful not to increase the range too much, because doing so may cause the correction to blend into areas where you don’t want the color removed.

You can then reduce the value for the applicable Amount slider to a more appropriate level. By fine-tuning the specific range of colors being impacted and the strength of the adjustment for each color, you can generally produce a great result. In some cases there may be a minor amount of fringing left behind, but generally with a bit of careful attention to the slider values you can achieve a very good (and often excellent) improvement for the photo.

Today’s Question: Canon has introduced a new 5DS R, a camera without a high pass filter over the sensor. This is supposed to make the image sharper. In Photoshop we use the high pass filter to increase sharpness. Please explain.

Tim’s Quick Answer: The short answer here is that the High Pass filter (in Photoshop for example) doesn’t truly sharpen a photo. Rather, it removes low detail areas of an image and retains high detail areas, creating contrast in the process. That contrast can then be used to sharpen with the help of a blend mode. A high pass filter on a camera’s image sensor filters out some of the low frequency information to avoid artifacts, but softens the image in the process of filtering out some of the information projected by the lens.

More Detail: In other words, both filters are doing approximately the same thing, but they are generally used in different ways. A high pass filter will filter out low frequency information and retain high frequency information. This is helpful in image sensors for preventing moire patterns and other visible artifacts in a photo. However, because some information is being filtered out, there is a degree of softness imparted to the image. In other words, there is a tradeoff here, but many photographers would choose a higher degree of sharpness and detail over the potential for removing certain artifacts in the image.

The High Pass filter in Photoshop also filters out low frequency (low detail) information in a photo, preserving (and enhancing) the high frequency (high detail) areas. The result is something of an embossed effect. When combined with one of the “contrast” blend modes (such as Overlay), this can create a sharpening effect. The light areas of the embossed copy of the photo will brighten one side of a contrast edge, and the dark areas of the embossed copy will darken the other side, resulting in the appearance of greater detail and sharpness.

So, in both cases the same basic filtering of information is being used for different purposes, but with variations on how those filters are implemented contributing to the difference.

Today’s Question: I read on a blog post that they thought 150 ppi is enough to print. Wouldn’t a resolution of at least 300+ produce a better image? Or is the print quality and ppi based solely on the size of the final output of the image – can a smaller print be printed at a lower ppi without sacrificing print quality?

Tim’s Quick Answer: If we use the pixel per inch (ppi) resolution as a form of “shorthand” for describing how much information is in a photo compared to the final print size, then we can use that ppi figure to talk about potential output size. To that end, I would consider 150 ppi to be too low a resolution value for most photographic prints. I consider values of around 200 to 250 ppi to be a good threshold for ideal output, and higher values are generally better. However, in most cases there is no need to go beyond about 360 to 400 ppi for output resolution.

More Detail: Part of the reason I think the general topic of resolution causes so much confusion for photographers is that we use so many different ways of explaining the same basic concepts. In addition, we often mean two different things when we use the term “resolution”.

Resolution can refer to both the total quantity of information as well as the density of information. When printing a photo, both of these concepts intersect.

To produce a print of a given size at optimal quality, you need a specific amount of information. If you’ll excuse analogy, imagine a photo inkjet print of being comprised of individual pixels on the printed page, something along the lines of tiny grains of colored sand you might otherwise glue to the paper to produce an image. It should be noted that photo inkjet printers use ink droplets of variable sizes, so this analogy doesn’t quite fit the reality of the situation. But hopefully it is a helpful analogy in any event.

Based on this analogy, we could say that a photographic print of a given size requires a specific number of grains of colored sand. While there are some added elements of complexity involved with a photo inkjet print, you can think of a print at a given size as requiring a specific amount of information. For a typical photo inkjet printer, that might require 360 pixels per inch. In other words, for a print at 8-inches by 10-inches, you would need an image that is 2,880 pixels by 3,600 pixels.

If you have less information than this, the printer (or the software being used to send the photo to the printer) will need to add information to the image. There is complex software at work behind the scenes to accomplish this task, but the bottom line is that if a photo doesn’t contain enough information to print at a given size, that information needs to be added in some way. Similarly, if a photo contains more information than is needed to produce a print at a given size, the “extra” information will be discarded.

Once you understand that a print at a given size requires (in a general way, at least) a given amount of information, you can choose to describe that information in a variety of ways. One way is to describe the amount of information in the image based on a pixel per inch (ppi) value.

For example, if your image was only 1,440 pixels by 1,800 pixels, you have much less information than you really need to produce the 8×10 print referenced above. If you do the math here, you’ll discover that instead of an image that represents 360 pixels per inch for the intended output size, you only have 180 pixels per inch.

The extent to which you can “get away with” having less information in your photo than is required to print depends on a variety of factors. That includes the degree to which your image is coming up short in terms of the amount of information (the number of pixels), the type of paper you’re printing to, the distance from which the final print will be viewed, the quality of the image you’re starting from, and other factors.

The bottom line is that your results may vary based on a variety of factors. However, in general I aim for having enough information in my image that I will at most need to enlarge by double the width and height (four times the total surface area). You can often produce even larger output, but the more you push the limits, the more likely you’ll be dissatisfied with the quality of the final print.

Today’s Question: I still need to calibrate my monitor – but I also read that just by bumping up the brightness to 20%-30% more, would be good enough to compensate for monitor brightness?

Tim’s Quick Answer: As far as I’m concerned, increasing the brightness of an image for the sole purpose of correcting for a print that is too dark is something that should be considered a last resort. Such a step should only be taken after troubleshooting the real reason the print is too dark and not being able to properly resolve that issue. While making an adjustment can certainly result in a print that better matches what you see on your monitor, I would generally regard this approach as representing a bad color management workflow. Also, the monitor should absolutely be calibrated before even trying to consider whether a print is too dark in the first place.

More Detail: When it comes to producing an accurate print, the desired result is often described as having a print that matches the monitor display. That is certainly our goal when printing, but it doesn’t quite explain what’s really going on. And I think that additional detail can be helpful.

What we’re really doing when printing within the context of a color-managed workflow could better be described in two steps. First, we want to make sure our monitor is presenting an accurate display of the information contained within our image, so that the adjustments we apply are based on an accurate view of the photo. Second, we want to make sure that the printer is producing an accurate print based on the information contained in the photo.

When the print doesn’t match what we see on the monitor display, the first thing to be done is figure out why the print doesn’t match the monitor display. If your print is too dark, it is quite possibly the result of the display being too bright. So if your monitor display is inaccurate, resulting in a print that is inaccurate, to me it makes absolutely no sense to change the print settings so that the printer is no longer producing a print that matches the information contained in the photo.

In other words, if your monitor is too bright, the solution is to set the monitor to an appropriate brightness level, not to make the printer produce lighter prints.

The first step then, is to calibrate and profile the monitor display so that what you’re seeing is an accurate reflection of the information in your photos. Most monitors with their default settings are about twice as bright as they should be. That is a full stop of light too bright. Calibrating the display will provide compensation for this issue, so that the brightness of the display is appropriate. That, in turn, will help ensure that the adjustments you’re applying are appropriate to the actual photo you’re working on.

You also want to make sure, of course, that you’re using a good profile for the printer, ink, and paper combination you’re using for printing, and that you’ve established correct settings in the software you’re using to print and in the printer properties dialog.

The bottom line is that you want to be sure that any work you’re doing in the context of color management is helping to make all of your devices (monitors and printers, for example) more accurate. Taking this approach will help ensure predictable and consistent results both when making prints yourself, and when sending photos to someone else to be printed.

Today’s Question: Two quick (I hope) questions about monitor calibration, based on an answer you provided recently: 1) You seem to suggest that I should disable the feature for my calibration software (ColorMunki) that will cause the display to adjust based on the current lighting conditions at my computer. Is that true? And 2) How often should I repeat the calibration for my display? The software seems to suggest every two weeks is necessary.

Tim’s Quick Answer: I do indeed prefer to disable the automatic ambient lighting adjustment for the display, and calibrating about every three months is more than adequate for a digital display, provided nothing has changed about your overall computer configuration.

More Detail: I fully appreciate that in theory it is a good thing to have your monitor display updated automatically to reflect the current ambient lighting conditions. For example, when the lighting in the room gets brighter because of the sun shining through the windows, the display will get brighter to compensate. The same holds true for the color of the display, again to compensate for the color of the ambient lighting conditions.

However, there are two basic reasons I prefer to disable this automatic adjustment. First, it introduces a degree of variability, and I very much prefer consistency in my color management workflow. Second, in my opinion it is much (much!) better to work in an environment with consistent lighting conditions, preferably in a relatively dark environment where outside light sources aren’t interfering with your monitor display. In other words, I prefer to make sure my working environment remains as stable as possible, rather than having my display calibration tool apply an automatic adjustment based on changing conditions.

As for the frequency of the calibration and profiling, this is something that changed dramatically when we transitioned from analog displays (such as CRT monitors) to digital displays (such as LCD monitors). Digital displays are much more consistent over time, and so you don’t need to calibrate and profile the display as frequently.

With analog displays I used to recommend calibration every one to two weeks, but I also knew photographers who would calibrate their display every single day. With digital displays, frankly it is perfectly reasonable to only calibrate every few months or so, provided there hasn’t been any change in the hardware or software configuration that would impact the appearance of the display.

The primary issue with digital displays is that they fade in brightness over time (although not very rapidly under normal circumstances). The color doesn’t tend to shift much at all, at least until the display starts to get toward the end of its useful life. Therefore, in most cases, calibrating every few months will ensure an accurate and consistent display.

Need a tool for display calibration? Check out the X-Rite ColorMunki Display:http://timgrey.me/colormunkidisplay