Sunday, August 24, 2008

I can't believe I haven't noticed this. Real color management in Firefox 3.0

I wrote earlier on how to enable color management in Firefox 3.0. It was great to see that finally a major browser next to Safari has color management, even if you have to go into a secret settings menu to enable it (see link above). At the time I assumed that the color management was just for images with attached tags. The same thing that Safari does. This would make Firefox, just like Safari, color foolish and causes lots of issues on Macs that are by default calibrated at a lower gamma than most windows PCs. However, and this was pointed out to me by outstanding photographer Greg Cope in a discussion on flickr, Firefox 3.0, with the color management enabled, color manages everything, CSS colors, text, and untagged images. If a page element has no attached profile, Firefox assumes sRGB. This is awesome and the absolute right thing to do. I tested it and it is absolutely true. If you have a Mac, enable this feature right away, even if you do not calibrate your screen. If you have a windows PC and you calibrate your screen, also enable this right away. On windows if you do not calibrate, the feature is not too useful as Windows assumes sRGB by default for the monitor profile. This brings Firefox quite a bit ahead of Safari and will make all web pages far better looking (no pale and too low contrast images anymore).

Saturday, August 23, 2008

Rusty old cars

These are some cool old rusty cars I saw in Silverton a few weeks ago. I love the colors on these. I set it up so that you can see a color and a black and white version. Click on the image for a larger version and to see more. All of the images are in this gallery and you can comment on them in my flickr stream.



Color

Black and white




Color

Black and white




Color

Black and white

Friday, August 22, 2008

Lightroom artefacts even show up when cropping

I don't know what causes the artefacts I talked about earlier. I do know they show up when you resize images on export. They also show up if all you do is crop your image. I have generated an example of this, again using the car image from before. I once exported the image uncropped from Lightroom to sRGB tiff, and I cropped it and again exported it. I took the two files into Photoshop, scaled them both to 200% using nearest neighbor scaling and aligned them to each other using the image align built in. Here is the result again using the mouseover trick. The default shows the image that was not cropped in Lightroom. I also include a substracted image that shows just the difference between the two calculated using apply image. The images can take a while to load after you hover so be patient. The change will be VERY obvious.


Not cropped in Lightroom

Cropped in Lightroom

Difference image



You see that is pretty bad. You see it is not just an extra halo that gets created, but also a sort of combing effect arises. Again Lightroom did not scale upon output. This was just the result of cropping. You can see these artefacts immediately in the Develop module in Lightroom when you just cropped.

P.S. I am not the first to point out this problem. Many people have done so before me (example link). I hope this will soon get fixed. You need light objects on dark backgrounds to see these effects (or the inverse). You see that even in pretty standard sort of images these problems can show up. If your image is not so sharp to start with this (the crop-induced artefact) will probably not be an issue. This was shot with a very sharp prime lens that outresolves the D300. However the resizing artefacts will show up even for less sharp images.

Wednesday, August 20, 2008

LR 2.0 review

Dave Girard from ars technica just posted a review of LR 2.0. I have always enjoyed his reviews and this is bound to not be an exception. If you're still on the fence on whether to get LR 2, go read this and you'll get lots of objective info.

Monday, August 18, 2008

Resize artefacts

I was reminded of this by a recent comment from Dorin. I have commented on this before. The resize algorithm used in Lightroom and ACR has a major problem on high contrast edges. Often you will see ringing artefacts. Here is an example of this problem using the truck image from before. I blew the images up 400% in Photoshop using nearest neighbor scaling to show you the ringing more clearly. The photoshop image has some jpeg compression artefacts that are not real. I forgot to scale to 400% before saving it. Just hover your mouse over the image to see the problem (first time it might be slow to show up).







As you can see, the LR scaling algorithm causes ringing artefacts on hard contrast edges. In this case it caused the appearence of a whole extra white band that is obvious even in the not scaled up image. This is WITHOUT any output sharpening applied. Applying sharpening makes this even worse as you can see in the truck image below. You clearly notice this in the full-size image when you're sensitized to them. Look for example at the roof and at the branches. I can often recognize images exported from Lightroom because of this defect. It's especially clear in silhouette type images, such as people against sunsets, or actual sunsets. Look in the black area here for example. I hope the Lightroom engineers will at some point tackle this problem as it has been known since the first LR release that this is an issue. Note also that this also happens when all you do is crop your image and do not scale upon output!

Sunday, August 17, 2008

On output sharpening

Lightroom 2.0 includes new output sharpening facilities in the export dialog, the print module and the web output module. These are extremely useful. The functionality is to correct for softness induced by the scaling for output and for the softness of the output medium such as a screen or a printing process. Here I'll talk about the use for output images for the web, email, etc. I used the export dialog scaled to 600 points for the long dimension and selected different levels of "screen" sharpening. Here is an example of a waterfall image. See (and buy prints of ;-) )the real image here. You can switch between different output sharpening levels by hovering over the names on top.


unsharpened

low sharpening

standard sharpening

high sharpening



To me, the difference between no sharpening and even just low sharpening is night and day. In the lychen details on the wet rocks for example. You wouldn't notice probably if you just have two images in different contexts, but you would probably thin-slice prefer the slightly sharpened one. The high sharpening is still very good in my opinion and works well for this image.

Here an another example of a cliché truck. This image has lots of sharp detail and you'll see that going to high has a different effect than on the waterfall image.

unsharpened
low sharpening

standard sharpening

high sharpening



Notice the extraordinary amount of extra detail that is pulled out in the hood area by the sharpening. This time, I think high is over the top and the best is probably low or standard. This is quite generally true for images that have man-made structures that have very sharp transitions. In general I have found that using standard gives very good results for most images, but of course this all depends on your taste.

Friday, August 15, 2008