Category Archives: technique

Sensor De-mosaicing and Southwest Colors

I have been pondering the way in which the method by which digital images are captured is affected by what is being photographed.  As part of my workflow, I render 1:1 versions of the images and then quickly weed out the ones that are not sharp.  This needs you to be able to see some detail in the shot that shows whether the sharpness is there.  I have found that, if a Southwest Airlines 737 is in the new color scheme, something odd happens.

Digital image sensors actually capture one of three colors.  Each pixel is sensitive to a certain color – either red, green or blue – courtesy of a filter.  They colors are arranged on the sensor in a pattern called a Bayer pattern.  The camera then carries out calculations based on what the pixels around each location see to calculate what the actual color should be for each location.  This process is known as de-mosaicing.  It can be a simple averaging but more complex calculations have been developed to avoid strange artifacts.

When I photograph the new Southwest scheme, something strange occurs around the N number on the rear fuselage.  It looks very blotchy, even when every other part of the airframe looks sharp and clear.  I am wondering whether the color of the airframe and the color of the registration digits are in some way confusing the de-mosaicing algorithm and resulting in some odd elements to the processed image that weren’t there in real life.  If any of you have photographed this color scheme, can you see whether you had something similar and, if you did or didn’t, let me know what camera you were shooting with so we can see if it is manufacturer specific or not.

Another Go at Stitching iPhone Raw Shots

As I posted a while ago, I have been experimenting with stitching shots from my phone.  Since I am shooting in raw on the phone, I have some latitude to play with the shots in post that wasn’t there before.  This time, though, I thought about it a bit more and put the camera into manual mode to fix the exposure.  This should make the stitching and blending easier than when it changed between shots (although, to give the Lightroom team credit, it did a pretty good job anyway).  I allowed plenty of overlap and the merge seemed to go pretty well.  Since it outputs a dng file, you still have the chance to edit more aggressively than would be possible with a jpeg.  Meanwhile, you get a higher resolution shot than with the internal pano mode.  This may be my go to method from now on.

It is Dark at Nellis During the Night Launch

On previous trips to Red Flag I have taken pictures of the departing B-1Bs as they fly overhead.  The burners are really impressive and definitely worth getting a shot of from below.  However, having done this a few times, I wanted to try something different.  The fighter get out of burner very quickly after they get airborne.  They are in mil power for ages before they get to you on the centerline.  I wanted to see what you could get from the side a lot closer in so Paul agreed to try something different.

We ended up shooting a lot of side on stuff of departures for the night launch.  Unfortunately, we didn’t appreciate just how dark it is at Nellis at night.  We had a good moon so we were hopeful that there might be some residual light.  It turns out that this is not the case.  Even close in, the fighters are out of burner.  The tankers and the E-7 went out and I got some shots but they were a struggle, event making use of the best high ISO capabilities of the cameras.  The B-1s did show up okay but I still didn’t do as well as I thought I should have.

I learned a bit about the performance of the cameras.  I was shooting at super high ISO settings with the camera wide open.  However, as I review the shots, I realize the camera was behaving in a way that I had not anticipated.  I was shooting in aperture priority with some negative exposure compensation dialed in.  As I look through the shots I see that the camera would start out with a dark shot, gradually boost the exposure and then go dark again.  I would review the shots and see one that was looking good but know that the next would be dark.

When shooting in such limited light, the shutter speeds are very low and the number of lost shots is high.  Therefore, you can’t afford to have the exposure be bad.  I don’t know how many shots I lost since they may not have been sharp anyway but I cut down on my opportunities.  In future, I need to have all of the exposures be acceptable in order to maximize my opportunities.  Therefore, I think I shall have to go fully manual on everything for these shots.  Set ISO up high and then go to manual aperture and shutter speed.  I will still lose a lot of shots but at least I can focus on dealing with my handholding technique rather than worrying about how the camera is metering a dark night.  It’s not too reasonable to expect the camera to get that right every time.  It is a pretty extreme case!

Blue Angels at Oceana (And High ISO)

I have only been to the Oceana show once.  I headed down there with my friends Ben and Simon.  We weren’t terribly lucky with the weather.  There was flying during the show but things were overcast and deteriorated as the show went on.  The finale of the show was, naturally for a big Navy base, the Blue Angels.  I was shooting with a 1D Mk IIN in those days and that was a camera that was not happy at high ISO settings.

The problem was, the light was not good and the ISO needed to be cranked up a bit.  Amusingly, if you were shooting today, the ISO levels would not be anything that caused concern.  Current cameras can shoot at ISO levels without any noise levels that would have been unthinkable back then.  However, I did learn something very important with this shoot.  The shot above is one that I got as one of the solo jets got airborne.  I used it as a test for processing.

I processed two versions of the image, one with a lot of noise reduction dialed in and one with everything zeroed out.  I think combined them in one Photoshop image and used a layer mask to show one version in one half of the image and the other for the second half.  When I viewed the final image on the screen, the noise in one half was awfully apparent.  It was a clear problem.  However, I then printed the image.  When I did so, things were very different.  If you looked closely, you could see a little difference.  However, when you looked from normal viewing distances, there was no obvious difference between the two.

My takeaway from this is that viewing images on screens has really affected our approach to images.  We get very fixated on the finest detail while the image as a whole is something we forget.  We print less and less these days and the screen is a harsh tool for viewing.

Puffy Cloud Backdrops

My personal preference is to shoot planes tight.  I like to see the detail up close and usually strive to get that in my shots.  However, sometimes I remember that there is more to it than that and there is something interesting about the context of the shot.  It doesn’t have to be a detailed shot of the plane.  It can be a wider shot when no one is looking at the plane expecting to see the intricacies of its structure.

Having some nice clouds to play with is an important part of the story.  Going wide when the sky is blue is not really going to add any drama.  However, some nice puffy clouds will certainly be appreciated in this situation.  In this case I was with some friends at O’Hare shortly after a storm had passed through.  Things had cleared up nicely but there was still plenty of evidence in the air of what had been dumping water on us a short while before.

I doubt closer shots would have been much use anyway.  With the amount of moisture in the air and the warmth that was quickly coming back now that the sun was out, heat haze would have destroyed an detail with a longer lens.  Going wider was probably the only option.  It was certainly worth it though.  The texture of the clouds after the storm was there to see and to be emphasized in the shots.  The plane provides a focal point to explore the image from but is not too important itself.  You can’t just do this but, from time to time, it is good to fight your normal style.

My Revised Workflow

My approach to processing images after a shoot is something that constantly evolves.  I have written about how I do this in the past but a few things have changed since I wrote that so I thought I would write up the latest approach in case it is of any use/interest to any other shooters out there.  I should say at the start that my workflow is based around the use of Lightroom.  If you don’t use Lightroom, this might not be of any use to you although I imagine that a similar process could be achieved with other software.

One thing to highlight at the start is that, when shooting aviation (and that is the majority of my photography), I aim to slightly overexpose my shots.  I have found that going a slight bit over and then bringing the exposure back down in post-production gives a better balance of exposure across the shots and also makes for more pleasing sky colors.  This is something I do when shooting RAW.  If you shoot in JPEG, this might still work but your latitude for adjustment afterwards is a bit reduced so you might not get the same effect.  I don’t shoot in JPEG so I can’t state what happens.

All the shots are imported in to Lightroom and I will form a Collection Set for the shoot.  I don’t have specific folders for shoots, nor do I have a renaming convention.  I keyword all shoots and this is how I manage files and find things later.  Keywording is a story for another day.  Within the Collection Set, I shall create a series of Smart Collections.  They vary depending on what I have shot.  There will always be Not Rejects, Rejects and Picks.  Then, depending on what else there is, there might be Videos, Time Lapse, Blend Stack, Pano Originals, Pano Edits, HDR Originals and HDR Edits.  I keyword any of these types of shot with that term so the smart collections will pick them up.  The Smart Collections may be looking for a date range or shoot specific keywords depending on what I have been shooting.

The aim for all of this is that I get a Smart Collection which is unrejected shots which doesn’t include and shots from HDRs, panos, time lapses or blend stacks.  I don’t want to get rid of those shots by mistake and I want to be able to edit those shots at a convenient time.  Then the Not Rejects folder becomes my focus.  I am aiming to get all of them roughly corrected for exposure so I can make decisions about which shots to keep.  I will be looking for sharpness/focus issues and exposure variation can really mess with how you perceive sharpness.  I will open a shot up in the Develop module and I will have the Grid view on the second monitor.  I can now select shots with the same exposure and choose Auto Sync.  Then a change to one shot will be reflected in all of them.

It used to be that I would select the shots by eye.  Then it occurred to me that the Metadata filter is powerful here.  I select the filter of shutter speed and then I can select each shutter speed in turn.  Now it is easy to select the similar shots and edit together.  This really speeds up the quick edit process.  I know tweak whatever needs tweaking and get everything basically okay.  I won’t bother with detailed editing unless a shot is going to be used for something further.  Now I select all files and, in the Library module, select Render 1-1 Views.  Then I head off to do something else for a while.

When the rendering is done (I don’t try and do anything else while it is underway because, while you can do other Lightroom tasks, everything gets pretty sluggish.  It is easier to wait.  I may even shut Lightroom down and restart it after the rendering is done because it seems to like the chance to clean itself up.  Then I go to the first of the Not Rejects shots.  I have it full screen on the main screen and then zoom to 100% on the second screen.  The Smart Collection is set up to show any file that is not marked as a reject (or all of the other stuff I mentioned earlier) so now I can click through the shots.  If a shot is good, I Right Arrow to the next one.  If it is bad, hit X and it disappears.  Now I can run through the whole shoot and quickly get rid of all shots that are not good, be they unsharp, chopping off a bit of something or just clearly useless.

When this first pass is done, I am now left with a bunch of shots, many of which are very similar.  Since I know they all are basically acceptable, I can now select all the ones that I won’t have a need for and hit X.  Very quickly I am down to a far more manageable number of shots.  Then I can pick which ones I want to do something with.  Hit P for those and they will automatically appear in the Picks Smart Collection and I can come back to them at any time.  If I have shots that will be used for a specific piece, I may create a Collection specifically for that publication and just drag the shots in so I can deal with them at any time.

That pretty much sums up how I handle a shoot.  Some will have pano shots, some will have HDR, occasionally there will be time lapses and often videos.  Sadly, the integration of video between Lightroom and Photoshop is non-existent so I have yet to have a good process for video editing.  Maybe one day Adobe will fix that.  They tempted us by having video in Lightroom but they never took it any further despite the fact that the opening in layers option for stills would be ideal for video editing.  One day…

Creating Lens Profiles for Adobe Software

UPDATE:  It turns out, the upload process for the profile sends to an address that doesn’t work.  While I try to fix this, if you want the profiles to use, you can download them by clicking here.

Within Adobe processing software, there is lens correction functionality built in to the Lightroom Develop module (or Adobe Camera Raw in Photoshop) that compensates for distortion and vignetting in the lens the image was taken with.  Adobe has created a large number of lens profiles but they never created one for the Canon 500mm in its initial version.  Adobe also has an online tool for sharing profiles but this does not include one for this lens either.  The 600mm had a profile and it was supposedly close so I had been using that for a while.  Recently, though, I was shooting with the 1.4x teleconverter fitted and this introduced some new effects which required some manual tweaking to offset.

I still wasn’t happy with the result so I decided it was time to bite the bullet and create some profiles from scratch.  Adobe has a tool for creating a lens profile.  It involves printing out some grid targets which you then shoot a number of times to cover the whole of the frame.  It then calculates the profile.  I was shooting at both 500mm and 700mm so I needed a few targets.  To make a complete profile it is a good idea to shoot at a variety of focusing distances and with a range of apertures.  The tool comes with many targets.  Some I could print at home but some of the larger ones I got printed at FedEx and mounted on foam core to make them more rigid.  Then it was time to shoot a bunch of very boring shots.

The software is not the most intuitive I have ever worked with but it eventually was clear what I had to do.  (Why do some manual writers seem like they have never used the process they are writing about?)  I found out how to run the analysis for different charts and distances separately and append the data to the profile as I go.  I did need to quit the program periodically because it would run out of memory which seems like an odd bug these days.  After much processing and some dropped frames as a result of poor shooting on my part (even on the tripod I got some blur occasionally with very slow shutter speeds) it got a profile out.  The proof of the pudding is in the eating of course (that is what the actual phrase is for those of you that never get past the pudding part) so I tried the profile out on some recent shots.  It works!  I was rather delighted.  I may shoot a few more samples in good conditions to finish things off but this was a rather happy outcome.  Once I have tweaked the profiles sufficiently, I shall upload them to Adobe and anyone can use them.

The Unusual Oakland Approach

Over the last few years I have flown in and out of Oakland more times than I can recall.  It has been my transit point for the majority of my travels.  A recent return brought me a new experience there though.  The airport is in two halves.  There is a main runway alongside the bay which is used by the airliners and is often the departure runway for the bizjets.  Then there are two further runways that are over near the old airport infrastructure.  These are used by light aircraft and for the arrival of bizjets.  (There is another intersecting runway but that doesn’t factor in this story.)

The normal approach brings you across the shoreline and over the water on the approach.  The other runways are on a different alignment and the approach comes over the local towns. I was looking out of the window and filming a hyperlapse.  I was a bit confused as I was seeing bits of San Leandro that I don’t normally see and we didn’t pass Hayward Airport.  We continued to descend over land and it was pretty clear we were not heading for the normal runway.  Sure enough we touched down on the old part of the airport prior to taxiing back and all the way across through the freight area back to the terminal.  I watched jets depart from the runway we had just landed on as well as from the normal runway so I have no idea what was going on.  I doubt I will experience this again anytime soon.

Time Lapse Up the Old Tower

My trip up the tower at SFO got me thinking about what things I wanted to get done while I was there.  One thing I had in mind was a time lapse.  I was a bit bothered, though, because we would only have about 20 minutes and setting up the camera and getting it going would eat into that time.  Fortunately, Nancy had just given me a new GoPro to replace the one I killed in Hawaii.  This one had a time lapse function built in.  Also, because it is small, it would be easier to get it close against the glass to minimize (but not totally remove) reflections.

When we got up the tower, I went straight to the window, hit the start button and leaned the camera against the glass.  I had no idea whether it was working or not so just left it and hoped.  I then started taking the other shots I was after.  When our time was up, I had to remember to go and get it again.  Only when I got home did I find out that it had taken a steady string of images.  I then processed them using my usual software of LRTimelapse aided by the lens correction in Lightroom for the GoPro.  The result is this video.  It is a little wide angle for some of the distant action and it would have been fun to have a longer time to capture images over but, overall, it worked out quite well.

Updating Your Keywording Standards

I provide a number of images to stock agencies.  They require keywords to tack what is in the images.  This has never been a problem because I have been keywording my images for a long time.  Some people keep their images in folders based on shoots but I have, for a long time, been more bothered about putting keywords in for my shots.  This way I can use Lightroom to find shots of any topic really easily.

However, I have become a lot more diligent about my keywording standards in recent times.  I used to not get too bothered about adding too much detail to my keywords.  Now, when I am looking for something, I search on a keyword but the result doesn’t show up an image that I know I have.  When I look at older shots, the keywords are rather sparse and not as specific as they would be now.

The result is that I am making an effort to improve my old keywords.  This is not a quick task.  I find little fixes I can make for clusters of shots and implement those.  It usually triggers something else I can do.  I don’t try and do everything at once.  I just build a list of little tasks and tackle them one by one.  I am now also more diligent about keywording new shots more aggressively.  Fixing this afterwards is a lot harder so now they all get tagged with everything relevant.  I hope this will eventually pay off for me.