I discovered that an earlier photo from the sunrise at Blue Lake (see yesterday's post) has an intriguing atmospheric effect in it. There are some subtle rays visible in the sky that appear to converge onto Mount Toll. Of course they do not actually converge but are parallel lines that appear convergent due to perspective. They look to be caused by light scattering of sunrise light in the high atmosphere that hits higher altitudes moisture before it hits the peak itself.
Sunday, September 28, 2014
Friday, September 26, 2014
On the day of the fall equinox, I went to see the sunrise at one of my favorite locations in the front range mountains, Blue Lake in the Indian Peaks Wilderness. My old friend Jean-David joined me. I don't often get to go out with others for these crazy sunrise hikes so this was great. We were greeted at the lake with very little wind, which is something that almost never happens in this place as well a fantastically colorful sunrise. A major treat. I took a series of images at sunrise with the same framing.
Thursday, September 18, 2014
I've written here about the color management problems with Lightroom on Mavericks before here and here. With the recent release of OS X 10.9.5, color management now appears to work right in Aperture and in iPhoto. However, it is still broken in Safari and preview. This is quite disturbing. Amazingly, both Chrome and Firefox do the color management right. It appears that Safari has built-in code to deal with sRGB tagged images because it treats them differently than any other embedded profile. It ignores the sRGB gamma curve and assumes it is the same as your display gamma profile! Below is a little test link for your pleasure to illustrate the problem. Rollover to switch between adobeRGB and sRGB tagged images. The sRGB image will have the darkest patches blocked completely in Safari. The adobeRGB image is correctly displayed. In Chrome on Mac OS X, since it is color managed, you will see only a very subtle difference due to the gammas being different in adobeRGB and sRGB and there therefore being subtle bit errors but both displays are essentially correct. The same is true for Firefox.
On a well behaved browser these two images should be close to identical. Safari in Mavericks (I tested 7.1) is no longer well behaved and completely destroys the shadows. It is important to note that preview.app is also broken but in a different way. Strangely it does not display black correctly. Aperture and iPhoto do behave correctly as of 10.9.5 but used to be wrong in earlier versions of Mac OS X Mavericks. Photoshop, since it uses its own color management routines, behaves correctly too. Lightroom only behaves correctly in the Library views as I have shown before. In Develop it has the same blocked shadow problem as you see in Safari. This problem is non-existent in 10.8.
Edit: Before any confusion arises, I need to explain the numbers in the images above. The sRGB version of the image shows the values of r,g,and b in the sRGB color space as encoded in the file. The adobeRGB version is the same file, but converted to adobeRGB color space in Photoshop. The numbers are still the r,g,b values of the patches in sRGB space, but the file is simply encoded in adobeRGB. The display should therefore be identical in correctly color managed environments as it is in Photoshop.
Saturday, September 6, 2014
I came across this scene driving back from the Vermillion Cliffs last spring. I had stopped at Bryce and Calf Creek Falls along the way and now was heading back home with vague plans to stop at Goblin Valley. on the way between Capital Reef (an extraordinary place I can also highly recommend) and Hanksville I got struck by the scene below of just seas of purple/pink flowers on the desert floor in front of the impressive buttes. I had to stop and take some pictures as you can well imagine. I think it is extraordinary how life seems to find a way in these places.
Tuesday, August 19, 2014
Sunday, August 10, 2014
I spent some time further quantifying the display problem that Mavericks introduced and that affects Lightroom, Aperture, and every other application that uses Apple color management libraries. In short, the problem is that shadows get crushed upon display. This is a serious bug that is remaining unfixed since OS X 10.9 and is apparently present even in the Yosemite beta. I am trying to raise awareness of this bug since I am getting no reply from Apple not from a bug report and not from directly emailing folks there. This should get fixed as it makes it tough to do serious work on Mavericks. You can work around it by using Photoshop which uses its own color management library or by using the soft proof feature in Lightroom. Mac OS X 10.8 and below do not have this problem and correctly show the shadows. This is independent of what color calibration you use and even shows up when you use Apple's supplied profile for your display.
I generated a simple photoshop file that has swatches of grey ranging from 1 to 100 in 8-bit scale and then used the system color taste dropper that you can get to if you open textedit and click the text color box. Then use "Show colors" and you can then "taste" any color on your screen and get the display values. These values are what is actually sent to the monitor and so are very useful for this purpose. Below I plot the values seen in Photoshop (correct), those in Lightroom Library and Lightroom Develop. I am not showing Aperture as those are the same as Lightroom Develop and also very wrong. I am using a double log scale to really show you the problem areas in the darker regions below r,g,b=25.
I did this using the nice plotly plotting service. The images sometimes take a short time to show up. You can find the data in the link on the bottom of the plot. Photoshop's light bump in the shadows is correct as sRGB has a little knee in the shadows. Lightroom Develop due to the Mavericks bug displays way lower intensity than it should leading to the crushed shadows that people are observing.
I also created the same swatch file in the color space of my monitor profile. The display of those swatches should happen at exactly the same display value as the input file. This really illustrates the problem I think.
Photoshop clearly does this correctly. The relation is almost exactly linear and any deviations are a single bit difference which is just a rounding error. Lightroom Develop shows way below. Lightroom Library is close but with a larger error than Photoshop. Below is the same data bit plotted as display error.
Mavericks causes Lightroom Library to be off by a full 8 points in the shadows! I hope this data is useful to somebody and helps some folks that have puzzled over dark shadows in Mavericks applications.
Saturday, August 2, 2014
Old man of the mountain flowers blooming at the shores of Andrews Tarn below Andrews Glacier in Rocky Mountain National Park. I visited this place after my visit to Sky Pond and Lake of Glass for sunrise. The mosquitoes were amazingly thick this morning and they were not impressed by the bug spray I was using ;-).