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LightRoom Print Job
The Print Job panel of Lightroom's Print module needs some explanation, because as it is, it looks fairly simple and straightforward, but it is also quite opaque about what each parameter is actually doing.
Lightroom's Print Job panel
Print to. In this drop down menu, you can decide to export the layout to a JPEG file instead of sending it to a printer. Instead of simply sending the image content to a file (as the Export function would do), this exports the whole page—that is, the image as well as the white border, the watermark, etc. This might be useful if you're sending the file to a professional print service—check with them about the appropriate parameters to use for resolution and color profile (a common requirement is a 300 ppi sRGB).
Draft Mode Printing. This mode is mostly self-explanatory, yet what needs to be said is that the image data used for the print is not extracted from the original files, but rather taken from the (lower quality) image previews contained in the catalog. Therefore, depending on the size of the previews you have configured Lightroom to generate, the quality of the draft print will be affected. (This might not be a problem if you are printing contact sheets, for example, since then the images are pretty small to begin with.) The advantage though, is that you can print in Draft Mode even if the original files are offline—all you need is for the images to have been cataloged.
Print Resolution. This parameter defines whether to resample the image data to a given resolution or to use the native resolution of the file (whatever is necessary to print the image to the desired size). Indeed, according to Adobe's documentation, checking that box and setting a resolution will "resample the image data if needed, depending on the print resolution and the print dimensions". It then goes on to say that "To use the native resolution of the photo (as long as it isn’t lower than 72 ppi or higher than 480 ppi), deselect Print Resolution."
As it's been said before, the general wisdom tells us that we do not want to resample our images if we're outputting the job to a printer (unless the resolution reaches extremes), so we should usually leave this box unchecked.
Now, this is a very important parameter that has seen its behavior change with each new version of Lightroom. Back in the original Lightroom 1.0, there was no way to disable the resampling, and this left many users unsatisfied—you should definitely update to at least 1.1 if you are in this situation, since Adobe swiftly addressed the issue and it was now possible to disable it.
But then in Lightroom 2.0, the whole output sharpening apparatus was rewritten as a result of a collaboration with PixelGenius (the guys behind PhotoKit Sharpener, the popular sharpening solution based on Bruce Fraser's seminal work on sharpening), and it was later found that the optimal result was not necessarily obtained by systematically using the native resolution.
Here's the crutial part:
- If you've performed the output sharpening on an image outside Lightroom (such as in a round trip to Photoshop), you definitely will want to use the native resolution—you do not want to resample an image that has already had its output sharpening carefully applied.
- If you're working on a raw file (or any other file that has not yet had output sharpening applied) inside Lightroom and you're using a version prior to 2.0, you also do not want to resample the image, as you will likely lose some quality, for reasons that have been discussed before.
- If you're working on a raw file inside Lightroom version 2.0 or more, then tests have seemed to indicate that you could achieve an arguably better result by upsampling the image by about 50%—that is, if the native resolution is, say, 240 ppi, you'll want to resample the image to 360 ppi. This remains true only if you are combining this with output sharpening (which will be discussed next) and only if you are upsampling—it remains true that you should use the native resolution rather than downsampling the image.
Print Sharpening. This parameter defines if Lightroom is to apply output sharpening to the image (which is not the same thing as capture sharpening, applied elsewhere in the Develop module, nor creative sharpening, applied locally). If you have already performed output sharpening on a file, you won't want to use additional sharpening and you'll leave this box unchecked. Otherwise, you'll definitely want to add some output sharpening.
According to Jeff Schewe, in relation to the output sharpening in Lightroom 1.x: "Low and Medium are useless—I can't see the result—and High is almost worthwhile." In other words, when using Lightroom 1.x, you'll likely want to use the "High" setting to apply a meaningful amount of output sharpening—or, better yet, perform your output sharpening in Photoshop before going to the print module.
In Lightroom 2, on the other hand, the output sharpening algorithm has been considerably improved, so as long as you've applied an appropriate amount of capture sharpening in the Develop module, using the "Standard" setting will likely be a good choice most of the time, making things really, really simple.
Naturally, sharpening is applied differently depending on the paper type used (if the paper has a coating or not), so you'll need to specify it under Media Type. According to the documentation: "Matte includes watercolor, canvas, and other nonshiny types of paper. Glossy includes luster, semigloss, photo gloss, and other shiny types of paper."
To finish off, don't forget to disable the printer color management and select the appropriate profile for the printer/paper/ink combination you're using. The "Relative" rendering intent is appropriate most of the time, but for critical work, you might want to go perform some soft proofing in Photoshop before deciding.
As for the 16-bit output, if your printer driver supports it (get the latest version), you should certainly use it. Even if the driver doesn't support it, if you're not sure, using the 16-bit mode won't do any harm—it'll just be useless and might slow down the spooling a bit.
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Resampling images for print
Regardless of the time an image takes to be spooled to the printer, resampling an image (i.e.: changing its pixel size using interpolation) is to be avoided, as resampling an image is detrimental to its quality.
The bottom line is this: if the native size of the image allows you to print using a resolution between 180 and 480 ppi, and if proper sharpening has been applied (considering the destination of the print, its resolution, etc.), you should let the printer do whatever interpolation is required.
Only if you intend to make a print so large that you have less than 180 ppi available, or if you intend to make a print so small that the resolution is above 480 ppi, should you resample the image. If you need to resample, keep this in mind:
- It is arguably preferable to resample by doubling (200%) or halving (50%), rather than using intermediate steps.
- For up-resing, the preferred algorithm is "Bicubic Smoother" — although you will then have to add a significant amount of sharpening.
- Output sharpening should always be applied after resampling.
For a detailed discussion on the topic of sharpening, refer to the Real World Image Sharpening book series. The Luminous Landscape also has video tutorials on the topic, notably chapter 12 of "From Camera to Print".
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Cancelling color casts
Color casts (overall color drifts) are avoided by using the appropriate white balance setting at capture time (the most accurate of which is a "custom" white balance), or by including a neutral reference in the picture for adjustment in post-production (such as a WhiBal).
Unfortunately, we don't always have time to follow this procedure, so we must often correct color casts arbitrarily in post-production. The problem is that it is not always possible to find parts of the subject which are of a neutral color, with which we can cancel the color cast. And even when we think something is neutral, chances are it is not really (who says this white wall was really pure white — it probably was yellowish!)
The quick and dirty solution is to pick something "close enough" as the reference for setting the white balance, and to adjust, subjectively, until we get something that looks more natural (completely neutral images often look unrealistic, too cold or too warm).
There is a trick to fix color casts in Photoshop which involves:
- Duplicating the image's layer;
- Applying an "Average Blur" filter on that layer (this reveals the overall color dominance);
- Inverting that layer (to obtain the opposite color of the cast, the one that neutralizes it);
- Changing the "Blending Mode" of that layer to cancel the color cast of the image.
Obviously, this trick can only get you so far — you still have to judge by eye what "feels right", by adjusting that layer's opacity, to apply more or less of the cancelling.
That being said, the procedure can be optimized to be executed faster and to render smaller files. Here's the trick. With a Smart Object of the image:
Apply an "Average" blur Smart Filter:
Create a "Curve" Adjustment Layer and use the "Gray Point" eyedropper anywhere on the image:
In a single click, you have set the three color curves to perfectly neutralize the average color of the image!
Color cast cancelling Curve Adjustment Layer
To finish up, simply delete the "Average" blur Smart Filter, which you don't need anymore:
You end up not with a new full-size layer of a fixed color (taking up disk space uselessly), but with a much more flexible "Curve" adjustment layer.
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Duplicating layers is oldthink
Back in the day, it used to be common practice to duplicate the final image layer to apply, for instance, output sharpening. The rationale was that this way, the original image would be preserved — the sharpening would only be applied on the duplicate, which could be thrown away at will.
Duplicate layer used for output sharpening
This also had the unfortunate effect of creating much larger files, as much more information would be required to save the two distinct layers (with all the downsides of larger files):
File size dramatically increased by using a duplicate layer
Luckily for us, later versions of Photoshop have provided a feature called "Smart Objects", allowing us to work with any layer (or any group of layers, of any type) in a non-destructive manner. Smart Objects can be transformed, warped, or have filters applied upon (called "Smart Filters"), without altering the original data. Sounds familiar?
Unsharp mask applied as a Smart Filter on a Smart Object
What's even better is that Smart Filters can later be edited — much like adjustment layers — or deleted altogether. Notice that this time, the file size is basically unaffected:
When using Smart Filters, the file size is basically unaltered
The Smart Object itself can also be edited, if need be. Double-clicking on it will open it as a new document containing the original layers, and all changes saved will be applied to the Smart Object that encapsulates the original layers. Even raw files can be turned (embedded) into Smart Objects: double-clicking it brings up Camera Raw and allows the user to further work on the image, without ever losing the flexibility of the raw format. (To open a raw file as an object, in Camera Raw, press the Shift key to turn the "Open Image" button into an "Open Object" button.)
If you'd like to apply a Smart Filter only to certain regions of the image, you can use the layer mask that is automatically provided when they are used.
If you prefer to work with the famous "High Pass" sharpening method, for example, you may be wondering if you'll be able to get rid of duplicate layers, as the effect used to be applied on a duplicate layer that later had its blending mode changed. No problem! In that case, you would use the "High Pass" Smart Filter on the Smart Object, and then open the "Edit Smart Filter Blending options..." dialog:
Blending options of a Smart Filter
You can there set the blending mode and opacity of any Smart Filter individually.
You can even use many filters simultaneously, and change the order in which they are applied:
Applying multiple Smart Filters
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Flat images on the web
Still following up on the working color space post...
It is sometimes said that images using the ProPhoto RGB or Adobe RGB workspace placed on the web will look flat because the browser converts the images to sRGB, resulting in a poorer rendition.
This is not what is going on.
As it has been said before, converting from a larger workspace to a smaller workspace is rarely a big deal, and is only really an issue for colors that fall out of the gamut of the destination workspace. If it was the case that browsers converted all images to the sRGB workspace, the effect would most of the time be very subtle. Converting an average image from ProPhoto RGB to sRGB does not result in an obviously globally flat-looking image. It would be a very wasteful, useless exercice in deterioration if this is what browsers did.
The problem with flat ProPhoto RGB/Adobe RGB images on the web is that not all web browsers (or not all versions of a given web browser) perform color management. Web browsers that do not color manage will simply presume that images are described using the sRGB workspace, regardless of the workspace they are really using. (Again, the following scale is arbitrary and is simply used to explain the concept.)
The ProPhoto RGB scale as presumed to be sRGB
If the image was using the ProPhoto RGB workspace, from the point of view of the sRGB workspace, all of its colors represent flatter colors. No conversion involved at all, it is just a matter of an erroneous presumption.
There is no question that you should use a browser that does proper color management if you can. To see if the browser you are using performs proper color management, visit this web page.
Nevertheless, even if you are using a browser that does proper color management, it certainly does not mean that other people do. You should always convert your images to sRGB before posting them on the web to reach a larger audience, as this is the common denominator.