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Exporting JPEGs for the Web from Lightroom
There seems to be quite a bit of confusion regarding the exportation of JPEG files from Lightroom. The "Export" window itself is rather straightforward, but you still have to know which setting is more appropriate for your needs. In particular, three settings may need further explanation.
Screen Sharpening
In a complete image processing workflow, there are commonly three different kinds of sharpening applied at different stages and for very different purposes.
It is important to understand that most of the sharpening is necessary even if one does not want to apply it "for effect", because of various limitations along the workflow. It should be noted that a basic sharpening workflow is not aimed at correcting soft images (caused by focusing error or motion blur), but at maintaining optimal detail in files that already contain as much as they can.
- Capture Sharpening (or Input Sharpening) is applied first and is necessary to restore loss of detail inherent in digital capture. That is particularly obvious when anti-aliasing filters are placed in front of image sensors to reduce moiré, as is very often the case (except on most digital backs, the Leica M9, and others). That is why the default behavior in Lightroom/Camera Raw and other raw processors is to systematically apply at least a basic amount of capture sharpening, which must then be refined manually (depending on various factors such as frequency). Note that this is true only when shooting raw files—shooting JPEGs means that the camera has already applied sharpening, so additional work on the file must be done carefully.
- Creative Sharpening is usually applied locally on specific regions of an image that require it most (such as the eyes and mouth when working on a portrait). This is the only kind of sharpening that is applied "for effect", where the photographer decides whether he wants his image to look natural or more crunchy.
- Output Sharpening is applied at the very end and is totally dependent upon the destination of the image. Luckily for us (and thanks to the work of Bruce Fraser and the guys at PixelGenius), Lightroom makes it incredibly easy to properly perform this task, which used to require a lot of trial and error. The thing is that if the image is going to an inkjet printer on glossy paper, the sharpening applied is not the same as the one applied for matte paper, and is not the same depending on the resolution of the print, and is very different from the one applied for viewing an image on screen. On one hand, inkjet printers inherently introduce a certain loss of detail because of the nature of the technology itself, so some additional sharpening must be applied—sharpening that would definitely look ugly if the image were to be viewed on screen. On the other hand, images need to be resized to be of an appropriate size for viewing on screen, and resizing an image calls for interpolation algorithms, which also means a loss of per pixel detail. This is why Screen Sharpening is required, not "for effect", but to maintain optimal detail when the image is to be viewed on screen.
Applying a "Standard" amount of screen sharpening to JPEG files exported for viewing on a web page is a very good idea—not to make the images look crunchy, but to retain an optimal level of perceptible detail.
Note that whether you intend to export images for the web or to print them, output sharpening is not something Photoshop will do automatically or even offer. When you want to do it yourself in Photoshop, the burden is on you to apply the optimal sharpening for a given destination—good luck! Do yourself a favor and just don't do it that way... Either print/export from Lightroom, or use PixelGenius' PhotoKit Sharpener and skip output sharpening altogether in Lightroom.
Resolution
When exporting images for viewing on screen, the resolution of the file has absolutely no meaning, so whatever value you put in that field has no importance and, contrary to what you might have been told, will have no effect on the exported file—files won't have more or less detail, and file size will not be affected at all. The important factor when exporting files for the web is the size (in pixels), not the "resolution".
Traditionally, images consumed on a computer screen have been set at 72 ppi (so you might as well put that), but that really depends on the resolution of each monitor—something you have no control over when you publish images on the web.
Color Space
If a file is going on a web page, because we cannot know if the browser used to view the image will support color management, we should aim for the common denominator (it won't support it) and choose the sRGB color space (the default presumption when color management is not supported).
The gamut of the sRGB color space is smaller than the gamut of the AdobeRGB (1998) color space, which itself is smaller than the gamut of the ProPhoto RGB color space—that much is true. But "color spaces" must not be confused with "color models".
The fact that most commercial printers offer very limited gamuts has nothing to do with the fact that they work in CMYK (a color model, not a color space). One simply has to have a look at Bill Atkinson's book to realize that commercial printers are technically able to achieve excellent gamuts and color fidelity when they put in the required effort.
In other words, the CMYK color model itself does not define the gamut, so it would simply make no sense to state that "CMYK has a smaller gamut than color space X".
4:34 pmOff
Index Files
It's been said that you should only have one "index" file per website—in the root folder. Well, you should definitely have at least one index file (in the root folder), but that would mean that you would have a structure such as this,
which would have the unfortunate side effect of creating rather redundant links, such as "/portfolio/portfolio.html". Well, yes, thank you, but I expected the portfolio folder to contain a web page for the portfolio!
Quite frankly, for such a simple website, the designer could just as well have opted for placing all the (html) files in the root folder, like this,
with all the relevant assets (such as images) placed in subfolders, of course. It could be argued that, for the sake of being super tidy, well structured, in case the website becomes bigger and assets get harder to manage, that it would be simpler for everything to be clearly separated in subfolders. True. But then for a bigger website, I would argue that assets would probably be managed by a database, not by a folder structure (which is kind of "old think"), so this would not be so important.
Now, if we want a compromise between the two situations, we will come back to the root of this post—index files. It just ain't true that you can't use multiple index files! It's only one index file per folder, not per website. You would get the following, very simple and straightforward structure:
By doing this, you would keep the super tidy structure, and as a bonus, you would also get simple links such as "/portfolio/". Also, if at some point you decide to add features to your site by switching from static html pages to say, PHP files, you wouldn't even have to update links...
2:05 amOff
Evaluating exposure via the Histogram
As you know, the image displayed on the LCD on the back of your camera is a poor tool to judge appropriate exposure—it cannot replace looking at your images on a proper display in a light-controlled environment. The trick, it is said, is to judge the exposure using the histogram—ideally applying what is known as the "Expose to the right" technique.
Moreover, as you also know, the image displayed on the LCD is not the raw file, it is a JPEG preview generated using the various parameters configured in your camera (white balance, saturation, contrast, etc.) Therefore, if your settings are such that the white balance is completely off the mark, for example, the image displayed will have a huge color cast. It's okay, since you know you'll easily be able to correct it later, because you're shooting raw.
What is less understood, on the other hand, is that the histogram itself is also not based on the raw data, but rather on that same JPEG preview! If you want to be able to judge the exposure using the histogram, how can you do it if the histogram is not based on the raw file? You can't!
...Well, let me re-phrase that: you can, but only up to a certain point.
What you should hope to achieve is a properly "exposed to the right" image—that is to say, an image that is exposed as far to the right as possible without clipping the highlights. That's a good thing, as we know that highlights hold more information than shadows, and what is nice about raw files is that they hold more highlights than what is possible when shooting JPEG. But how are we to know how far we can go if we base our judgement on a histogram that was built around a JPEG?
The idea is to use a set of parameters in the camera that will render the flattest JPEG preview, so as to generate the most generous histogram possible—regardless of the fact that it won't really matter in the end, as you are shooting raw and these settings are irrelevant to the final development of the image. If we were, for example, to use highly saturated colors and contrast to generate the JPEG preview (and, as a corollary, the histogram), we would be fooled into thinking that certain channels would clip before they actually do. Here is what you can do to render the most generous histogram possible:
- Use a bigger color space. If the camera allows you to use Adobe RGB (or even bigger) instead of sRGB, this will considerably extend the range of the histogram.
- Use minimal saturation and contrast. With Canon cameras (there are similar parameters in other brands as well, I am just not familiar with them), use a Faithful or Neutral "Picture Style", which will turn all the switches down.
- Use a white balance that is "close enough" to the actual lighting conditions—even if you intend to use something very different later, for effect. If you pick a Daylight white balance and shoot under tungsten light, for example, you might be fooled into thinking that the red/green channels are clipping before they actually do, as the JPEG preview will have a huge yellow color cast.
Needless to say, this will render a fugly image on the LCD, that will look completely washed out. Don't worry, you shouldn't be judging color/tint/saturation on the LCD anyway—do it for the greater good of a more reliable histogram.
Remember that the raw file still manages to contain more information than even this better histogram can display (because you will process the file using a bigger color space still, ProPhoto RGB), but at least you'll be much closer to the real thing.
1:24 amOff
Keywording in Lightroom
Some precisions on keywording in Lightroom...
As you know, instead of adding tons of keywords to a single endless list and spending a long time trying to find them, a good approach is to create a hierarchy of keywords. You could have a simple tree of keywords such as this one:
Example of a hierarchical keyword list
Contrary to what you might have been told, when you select a child in a hierarchy, this automatically includes all of its parenthood in the list of keywords attached to the image—not only the child. The confusion comes from the fact that in the Keyword Tags list, the default option ("Enter Keywords") only displays the keywords that were entered/selected explicitly. If you pick the "Will Export" option, on the other hand, you will see the actual list of keywords that will be exported with the image. This reveals that, indeed, the whole hierarchy will be included:
Choosing "Will Export" reveals the true list of keywords exported
The only exception to this rule is the keywords that have been configured as "Private"—that is to say, that have their "Include on Export" option disabled (such as the root keyword "PLACES" in this example). Notice that, therefore, creating a hierarchy containing variants of a single word (such as plural forms Women/Woman) is not a good strategy, because selecting the child item would automatically include the other version as well.
The same way, you can avoid a lot of redundancy by using a hierarchy. If you were to create a sub-category for "kinds of trees", for example, you wouldn't need to call each tree "Palm Tree", "Oak Tree", "Elm Tree", etc., as the parent is called "Tree", and picking any one of them would already include the parent keyword "Tree".
Once you have keyworded your images, all you need to do to filter the images that were tagged with a specific keyword is to click on the arrow at the right of the keyword (it shows only when you hover the mouse pointer over the area):
Filtering by Keyword
As with any other metadata, these settings will be saved in the Lightroom Catalog, but contrary to what you might have been told, they can also be saved into the XMP sidecars or embedded into DNG, PSD or JPG files—the automation of which only depends on the settings of your Lightroom Catalog.
In the "Metadata" tab of the Catalog Settings, if you pick the "Automatically write changes into XMP" option, every time you make a change (be it keywords, develop parameters, crop, whatever), they will be saved into the actual files right away—not strictly kept inside the Lightroom Catalog. This means that even if you were to browse these files from within another compatible application (say, Adobe Bridge), you would indeed see all the metadata.
If you disable the "Automatically write changes into XMP" option, you can still force the settings to be saved to the files, but you have to do it manually. You can have Lightroom display whether the metadata have been saved or not as an icon in the Library Module:
"Metadata needs to be updated" icon
To trigger the update, either click on this icon, or select the files and use the "Control/Command+S" shortcut (this is helpful if you have a bunch of files that need updating).
4:49 pmOff
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.