This blogpost has nothing whatsoever to do with colormanagement or editing. It originated purely out of frustration and bewilderment of the online photo community. You might call it a rant, and it should be read that way: Take it with however many grains of salt you like.

“Great Image”

… That’s a phrase I see quite a bit variations of when browsing photo sharing sites and forums and, lately, Twitter.
All to often though, I look and the image and think: “No, it isn’t great”. Heck, in some cases, the image isn’t even what I’d call “good”.
Why these comments then? It might be because people don’t understand the value criticism can have and want to be nice…
Well, guess what: In my opinion, about the worst comment someone can make about my photos is “nice image”: I know it’s “nice”, otherwise I would not have posted it. But I also know it isn’t perfect. In fact, I can pretty much guarantee that I see flaws myself in every image I make. I see them, and because of that I can hopefully avoid them next time. But because I’m not perfect, I might overlook other flaws. Since I want to continue learning, I’d like to have them pointed out: I prefer input over praise.

What’s criticizing then?

According to Merriam-Webster:

Definition of CRITICIZE
intransitive verb
: to act as a critic
transitive verb
1
: to consider the merits and demerits of and judge accordingly : evaluate
2
: to find fault with : point out the faults of
— crit·i·ciz·able\-?s?-z?-b?l\ adjective
— crit·i·ciz·er noun

If you look at the first definition, you’ll see criticism needn’t necessarily be unfavorable. And even if it is, I still think it’s a good thing.

Why is giving criticism good?

Seems like a lot of people think that criticising must be negative, since you are pointing out what you don’t like. What they fail to take into account is that by giving criticism, you are analysing an image. Looking for “merits and demerits” according to the above definition. And by doing that, you learn: You don’t just look at an image, you think about it. And by thinking about images, you also learn to recognise certain things, not only in the image you are looking at, but also in images you are going to shoot yourself in the future. On one hand, you look more analytical at composition, exposure, whitebalance and other technicalities, but on the other hand you probably have a “gut feeling” about an image. You might just be able to figure out what causes that feeling, so you’re later able to use it to your own advantage. Fundamentally, it’s my idea that by analysing other peoples images, you learn about yourself.

Why is receiving criticism good?

Everybody learns from making mistakes, but only if you know you made mistakes. So sometimes these mistakes need to be pointed out to you. Also, you might get an idea whether you are “on the right track”: What do other people think about your style? Because they didn’t shoot the image, they have a different relation to the subject, and might be able to look more objectively.

How to be a good critic

Of course, you don’t need to only point out negatives. A bit of sugar-coating praise might help overly sensitive people deal with accepting their images aren’t perfect. If I cannot find anything positive to say about an image, I either don’t comment at all or, if I’m feeling frank, I say I don’t like it and try to explain why. Just saying “this image sucks” is about the only comment that’s worse then “nice image”.

Time to be honest

So, all go visit your favorite forum or photo sharing website, and be critical. Everybody should benefit from that.
Obviously, if you are critical about this blogpost, feel free to post a comment as well.

Simply put? Nothing.
Well, if that were all I had to say on the subject, this would have to be my shortest blogpost ever… Okay, a bit more info then:
A lot of first time DSLR users are concerned that their shiny new camera delivers files that are “only” 72dpi, while their old point and shoot delivered 300dpi files. Why is this concern unwarranted? Surely 300 is more then 72, and more is better, right?

Wrong

The old wisdom saying is that “300dpi is for printing and 72dpi is for screen”.
There are a few things wrong with that.
First and foremost, the term “dpi” stands for dots per inch. In a digital file there are no dots, only pixels. So the correct term is pixels per inch (ppi).
Also, 72ppi originated as it was the resolution of an ancient Mac monitor. Current monitors have a much higher pixel density: My old 12″ PowerbookG4 for instance has a screen resolution of about 100ppi. Most current screens are somewhere between 80 and 120ppi.

Do the math…

for your screen: Simply measure width and height and divide the number of pixels by the measured values… Tip: Once you found the figure for your screen, be sure to enter it in the PSCS4 preferences under “Units and Rulers, Screen resolution”: That way, the “Zoom, Print size” will show an accurate sized preview.
So, is a 300ppi file better then a 72ppi file?

No difference

If you hadn’t gathered as much from the above, for display on screen, only the display you’re using will determine the “resolution”.
So, a file that contains for instance 500×750 pixels will be displayed at a different size (in inches, centimeters, or whatever you prefer), depending on the screen you’re using to view it. The arbitrary ppi figure set in the file has no relevance whatsoever.

To illustrate that, here is an example: Each file is 500×750 pixels. One is 72ppi, the other 300ppi.

Notice the difference? No? That’s because there isn’t any.

Why use it then?

Because you have to put something in the box: There is no way that Photoshop will allow you to not fill in a value. However, what you put in there is pretty arbitrary. Use whatever you like basically for display on screen.
I prefer to use 300ppi for general use, since then the “image size” dialog box will quickly tell me about how large I can print an image at decent quality. For web, I mostly use 72ppi (unless I forget) since, well, that’s what some people expect…

Some more reading: here

Adobe Photoshop Lightroom, like many other Raw converters, has a clipping warning.
The purpose of it is to give you a visual warning (apart from the histogram) of what parts of an image might be clipping.

What is clipping?

A pixel is clipping when it reaches a value of 0 or 255 in one or more channels, and “should have gone further”. Since it cannot go lower then 0 or go higher then 255, it remains at those values: Detail is lost if one or two color channels clip, part of the image is solid black or white if all 3 channels clip.

The effect of color space

As with anything in digital imaging, the color space used has a big influence: A wide gamut color space (such as ProPhotoRGB) will have lower values for the same color then for instance sRGB. So a color that is clipping in sRGB, need not be clipping in ProPhotoRGB!
This color for instance, has sRGB values of (250,40,30). The ProPhotoRGB values are (177,76,36) for the exact same color.

This means that you have a lot more “headroom” in ProPhotoRGB before you hit the “clipping wall”.

So what?

Lightroom uses MelissaRGB internally (ProPhoto RGB with sRGB Tone Response Curve).
The histogram in Lightroom is based on its internal working space. So when you are exporting images for a web gallery, the images might be clipping big time while Lightroom is not warning you!

An example

I opened a DNG file in Lightroom 2.4 and in ACR 5.4. These have basically the same raw conversion engine. The exact same settings were used in both Raw converters.

Here is the image, histogram and clipping warning in Lightroom. (click image to open bigger).
Almost no clipping indicated (It makes no difference what output color space you choose): Just a bit in the lower right that goes almost black, and absolutely no clipping highlights according to Lightroom:

Here is the image in ACR 5.4. Output color space is ProPhotoRGB: About the same clipping warning Lightroom is giving.

Here is the same image in ACR 5.4. Output color space is sRGB: major clipping!

For reference: Here is the image exported out of Lightroom: Clipping indeed:

Workaround

Is there a workaround? No (except using ACR that is).
Simply sad said, the only thing you can do is watch the histogram, guess, and use your eyes. If your screen has close to sRGB gamut, clipping in sRGB might also be visible on screen (as can be seen from the above screenshots in Lightroom).
If you use a wide gamut screen however, you might see quite a difference between the Lightroom “Develop” module and the actual exported image…

for a web gallery.
Normally, Lightroom will only let you preview sharpening and noise reduction at 100% view. This is a good thing™ in my opinion, since it is capture sharpening, meant to negate the effects of an anti-aliasing filter in front of the sensor. You’d get all kinds of moiré without an AA filter, as can be seen in the hilarious story Eamon Hickey wrote about the NC2000.
Since the AA filter softens the image a bit, you need to sharpen it. This is input sharpening. So it should be judged at 100%. Unlike output sharpening, which is better judged at reduced size, at least: For print. For web view at 100% and WYSIWYG.
Or is it?

A workaround

I recently was processing a few ISO 6400 images, which had severe noise in them. Here I ran into the problem that the NR isn’t shown at “fit window” view. So I had no way to judge what the images would look like online.
(all images can be clicked for a larger version)
This is the image as shown in the develop module:

This is part of the image at 100%:

Clearly, no NR is shown in the “Fit screen” view.
What works however, is to create a 1:1 preview (In LightRoom > Library Module > Library > Previews > Render 1:1 previews), then look at your image in “Loupe” view (shortcut: “E”) at fit to screen. Bingo. Both input sharpening and NR are applied. There is no way to get LR to preview output sharpening.
This is the image at fit screen in the Loupe view before and after creating a 1:1 preview:

Web Gallery

The beauty of this is, that it also works for the web gallery: If you preview it in LR after making 1:1 previews, you will see the image as it goes online (minus the output sharpening that is)

The image in the web gallery preview in LR, before and after creating a 1:1 preview: An even bigger difference:

This is the final image as it was exported by LightRoom. Inclusive output sharpening.

Pretty neat, huh?

A lot of people are confused the first time they save an image for web display: The image looks different in a non color managed browser then it did in Lightroom or Photoshop. One “solution” was to view the image in Photoshop like it would appear in a non color managed application, by going View > Proof setup > Monitor RGB. This would show you how the image would look in a non color managed application on your screen. Still a guess what anybody else would see though, since you’re seeing the difference between the monitor profile and sRGB…

Better

A much better option would be for everybody to browse color managed.
Up until recently, most browsers were not color managed. Safari changed that, and was the first color managed browser for PC. Internet Explorer had provided a color managed browser for Mac OSX before that, but it is discontinued now.

A few new options arrived lately

FireFox 3 is color managed, though the feature is disabled by default. If you enable it, it’s a heck of a lot better then Safari in my opinion, since it fully color manages: It rightly assumes sRGB on untagged images (Safari stupidly assumes Monitor RGB, except on Vista), and it does so for backgrounds as well. So no more Safari Wonkiness…

Firefox gets even better tomorrow, when version 3.5 is introduced. It has color management enabled by default.. There is a bug however when using wide gamut monitors. So those of you on a wide gamut screen, better wait for version 3.5.1…

Easiest way to enable color management in FF3.0, is to use the Add-On. Nice to note that this Add-On also works for Flock, the browser I’m currently using.

OmniWeb 5.1.3 is color managed when set to be in the prefs.

Another color managed browser will be the upcoming version of Google Chrome. Yay!

Join the majority

Looking at the statistics of this blog, about 53% of the visitors use Firefox, 21% use Safari, 19% use IE and 3% use Chrome. So chances are that a whopping three quarters of you could be browsing color managed! That’s a big majority.

Since more and more people will be browsing color managed, the last part of the advise many times given in the past; “web images should be sRGB, without embedded profile“, is no longer valid in my opinion. Also, a lot more people use wide gamut screens, on which non color managed browsing is a horridly over-saturated experience.

Where does Photoshops “Save for web” fit in?

The save for web dialog box changed a bit after CS2, and now also gives you the option to convert to sRGB. In PSCS2, you had to do that manually. It still gives you four different ways to preview your image: The same options you get when you go View > Proof Setup.
What a lot of people don’t realize is that these viewing options can be set for each window separately.

First, let’s see what each option does:

“Monitor Color“: As a non color managed application would show it on your screen.
“Macintosh (No color management)” As a non color managed application would show it on a monitor with gamma 1.8 (ancient): The image appears lighter.
“Windows (No color management)“: As a non color managed application would show it on an sRGB monitor. An sRGB image will look the same here as in the last option. An AdobeRGB or ProPhotoRGB image will appear less saturated.
“Use document profile“: As a color managed application would display it.

What does it look like

For demo purposes, I used an image in ProPhotoRGB that shows a massive amount of clipping in sRGB. I also used my laptop, which has a rather crappy screen, so the differences between the monitor profile and sRGB are obvious.

The window showing the “Original” is set to “Document profile” in all screenshots. Again: You can set the view for all windows separately. So when using “4-Up”, you can compare the original to an approximation a wild guess of what non-colormanaged browsers might show other users.

First screenshot: ProPhotoRGB, without converting to sRGB, Preview set to “Monitor Color”. Horrid, and the reason for many posts on photography forums.

Second screenshot: converted to sRGB, Preview set to “Monitor Color”. Quite a bit off, but does show why you should use sRGB for the web.

Third screenshot: converted to sRGB, Preview set to “Document Profile”. Nice Match.

Note that the image is way out of the Powerbooks gamut. So it appears a lot less saturated in that color space, because it’s clipping like crazy. (Naturally, the screenshots were converted from the powerbook profile to sRGB before posting) Compare the sRGB version below with the one restricted to the Powerbooks displays gamut in the above screenshots.

Additionally, the clipping that’s occurring while converting to sRGB doesn’t show on the Powerbook, since the monitor gamut is smaller then sRGB. On my desktop with LaCie CRT, I can clearly see the clipping when toggling the “convert to sRGB” tickbox. If I were to post this image, I’d correct for that clipping before converting…

So, all in all “Save for web” is a very useful tool that provides not only “WYSIWYG” , but also provides a guess to what others might see.

Lastly, for those interested: Here’s a screenshot of the difference between Gamma 1.8 and 2.2. A good reason to use Gamma 2.2 and I’m glad to say the next version OSX will finally ship with Gamma 2.2 set as default, instead of the legacy Gamma 1.8.