Workflow for editing your aviation photos V1.1 Jan. 2010

Transcription

1 Workflow for editing your aviation photos V1.1 Jan

2 Content Workflow for editing your aviation photos V1.1 Jan Basics Editing Correcting the horizon Cropping Adjusting the levels Understanding different types of histograms What does that mean for my editing? working with curves Adjusting curves directly in the photo adjusting colour brightness and contrast done with the first adjustments reduce noise Resize remove dust spots basic sharpening advanced sharpening Advanced sharpening technique to reduce noise in the sky Saving the photo for upload Editing Tricks Shadow and Highlight tool Lens Correction filter Useful Photoshop shortcuts Setting up the camera for easier editing File Format Important for shooting JPG

3 1. Basics I will use Photoshop CS2 for the guide; any other version of Photoshop or other photo editing programs should be able to do the same. I have added some information for Photoshop CS4 as well. 2. Editing As an example I will use one of my photos. I choose one of the typical spotting shot with many flaws, but a quality that should be easily possible for you, if you have a decent control and knowledge of your camera and its settings. 2.1 Correcting the horizon The first step to do is to correct the horizon. For that we will use a vertical reference in the photo, like the edge of a tall building. Masts and lamp posts are generally not good reference points, as they can lean to one side in reality quite often. The runway itself might be a good - 3 -

4 reference, but on some airports it slopes, so it is not suitable then. Your main reference however should be vertical structures. For levelling the photo I use the measure tool and draw a line along the side of a vertical structure. It is a good idea to set the background colour to something colourful before you start with levelling the photo. Using the measure tool See that it has been selected. Now draw a line that matches a vertical reference object. Then you go to Image -> Rotate Canvas -> Arbitrary This opens a box, in which the amount of rotation is already entered based on your use of the measure tool. Click ok. The photos is rotated as needed, you know should check if the result is balanced. Are the verticals in the centre really vertical? Do the verticals on both sides look good? If you used a wide angle lens, both sides should show some difference to being fully vertical, the centre must be correct. Finally check with available horizontal reference objects. If everything looks well balanced, you are done, if not repeat the steps for levelling the photo until it is perfect. After that your screen should look like that

5 2.2 Cropping Now it is time to crop your photo down to the allowed sizes of the website. Usually a crop ratio of between 4:3 and 3:2 is acceptable. In pixel this is: Pixels wide Pixels high (4:3) Pixels high (3:2) I prefer using 3:2 crop for typical side on shots like the example. You click on the crop tool and enter 3 cm and 2 cm into the X and Y fields- Do not enter anything into the resolution box. Another option is to enter the pixel size you want into the tool settings. So you should enter 1280px and 960px for example

6 Crop tool selected and settings for a 3:2 crop entered Pull up the crop box and try to keep the centre in the middle of the aircraft, typical on the height of the window line. crop tool in use aircraft centred. Be careful that you do not have parts of the plain background from the rotation in the crop. At this point selecting a colourful background colour (as described in 2.1) pays off

7 2.3 Adjusting the levels The next part of the editing process is to work on the perfect exposure of the photo. For that you need to create an adjustment layer You do this by going to your layers toolbox (F7 opens it) and the clicking on the black and white circle in the lower middle of the toolbox. (Create fill or adjustment layer). How to create an adjustment layer for levels Then you adjust the histogram until it looks like this

8 Adjusting levels In the example the exposure was pretty ok, out of camera, so there was only a little work to be done, but you might experience other cases in which you have to adjust the histogram much more. It might look like that: Then you have a photo that lacks contrast. You must then move the slider for the black point and the white point to the edges of the curve in the histogram. This can be easily fixed and you have not lost any information in the photo, you just did not use the whole dynamic range of your camera while shooting the photo

9 This is more or less the same basic problem. No black parts have been recorded. Simply move the black slider in PS to where the histogram starts. The image will look bright and lacking contrast. In that case the photo will look a little dark. Just move the white slider to the correct position and it will look better. Much worse however is a histogram that looks like that: Here you have too much (too hard) contrast. Information has been lost. Some parts have been recorded as pure black; others as pure white, in both fine details have been lost. This is not possible to recover in editing, so it is something you want to check on your camera while shooting. If the histogram in camera looks like that, turn down then contrast in the camera settings. General advice: check the histogram in camera regularly If the histogram is clipped at the left or right side you need to adjust your exposure. (+ if it is clipped on the left, - if it is clipped on the right) - 9 -

10 2.3.1 Understanding different types of histograms Most modern cameras can display a luminosity histogram and a RGB histogram. The RGB is most often displayed with all 3 channels given in separate diagrams. Photoshop is also able to display different types of histograms. I will explain how to do that in CS4. Go to the View pull down menu and activate Histogram. Our example should then look like this. You can see the histogram as the second info area from the top. The default setting is RGB. This histogram combined the values from the Red, Green and Blue channel into one single graph

11 RGB histogram The other very useful type is the luminosity histogram. It disregards colour and just measures the brightness of the pixels. Luminosity histogram Simply said that is the histogram you would see in the RGB version, if you would convert your photo to B+W. (you can try it to see the effect)

12 Colours histogram The third useful histogram version is the Colors histogram. There you can see the distribution of colours. But this is only interesting in some special cases, or to get an idea in which part of the photo your white balance might be off. In editing we use the histogram in the levels function to correct the exposure and the contrast. But as shown in the previous section, different types of histograms show different information. If we take a look at the RGB combined histogram and the luminosity histogram shown in the previous part, we see little difference. RGB histogram on the left and luminosity on the right But if we look closely we see that the graphs do not really match. The peaks are different. So let us take a look at the histograms of the individual colour channels

13 Red, green, blue and RGB We can see that the first 2 peaks from the left are mainly created by the blue channel. The third peak is mainly green. While only the highest peak is a combination of high peaks in all 3 channels. The individual colour channels show black on the left and 100% red, green or blue on the right. A pure white in the RBG is the addition of pure red, green and blue. To make it easier to understand we add a 100% red rectangle to the otherwise unchanged photo. Now let us take look at the RGB histogram again

14 We can see that on the left and on the right the graph exceeds the scale. As explained in Part 2.3 this could be understood as a sign of too much contrast with overexposed parts and pure black parts. But we know that there is no overexposure, as we did change nothing, but adding the red rectangle. This is caused by the fact that the RGB histogram combines the value of the three colour channels in one graph. So take a look at the three individual channels. Red, green and blue histogram As we can see the red one shows a peak at 100% bright, blue and green show a peak at 100% black. Obviously this is caused by the 100% red square. As the square is 100% it shows as 100% red (bright) in the red channel and as 0% (black) in the green and blue channels. The combined RGB histogram therefore shows peaks at both ends. Now let us take a look at the luminosity histogram for the photo with the 100% red rectangle

15 Luminosity histogram of the picture with the red rectangle on the left and without on the right As you can see there is little difference between the luminosity histogram with the red rectangle or without. Which makes sense as 100% red is neither very bright nor very dark What does that mean for my editing? As shown in the previous chapter, the RGB histogram can be fooled by areas that are strongly red, green or blue, or parts that are missing one of those colours. So to perfectly adjust the levels and the contrast of your photo it is a good idea to have the luminosity histogram shown in PS while setting the levels. In CS4 it does adjust to the changes you make in the adjustment layer in real time. So if you are working with the level toolbox, there is one easy trick to make your editing easier. As we have learned, a clipped histogram does not mean over exposure or underexposure every time. To see which part do cause the clipping on the dark or bright side of the histogram you can do the following. Hold down ALT key and left click on the white or black triangle directly under the histogram. The photo will now show you which parts of the photo are responsible for the peak. Using the example photo here is how it looks when I click on the white triangle

16 As you can see the peak is mostly caused by pure red parts and only a tiny portion is white. And here is how it looks when clicking on the black triangle, which should show you all pixels that cause the clipping on the left side. As you can see very few parts are really black. Most of the clipping is caused by the green channel. Which makes sense as we had areas with 100% red, so they must have 0% green

17 2.4 working with curves First you have to create an adjustment layer for curves, exactly the same way you did for levels, just click on curves instead of levels. Our example lacks a little contrast so we will use a curve to correct this. Curves used to add contrast By using a curve formed like an S you can add contrast to a photo. The curve tool needs a little of explanation

18 This is the diagram you see when first opening the dialogue. The horizontal axis represents the brightness value of the original photo. The vertical axis represents the changed brightness levels (output levels). The diagonal line shows that the value for the input level is the same as the output level. To make changes to this curve you need to map pixels on the diagonal line. You do this by clicking on it. More then 3 points are usually not needed. You can then change the output levels by clicking on the map points and holding your mouse button down and moving the points. With preview selected you should see the changes to your photo in real time

19 Some prefer to work in Labmode when adjusting curves, but working in RGB works fine. For aviation photography there are 3 basic curves that are most useful. The classic S-Curve. It is good for adding contrast to the photo. As you can see it brightens up the light tones and darkens the dark tones, while the changes to the midtones are small. Used with inverted settings it can be used to brighten up darker parts of a picture. But it does reduce the contrast then. The next one is the M-curve. It is most useful to work out the contrast in a cloudy sky. However it must be used with care, as it might reduce the contrast on the aircraft or even create a slight overexposure on white planes

20 One of the most useful is a simple curve that brightens up the midtones. It is a very effective way to correct a slightly dark photo, which still looks too dark after adjusting the levels. With those 3 basic curves you should be able to achieve everything that can be done by the shadow / highlight tool, without risking to create strange halo effects around your aircraft. General Advice: Some editing programs like Photoshop Elements do not come with a curve function. But there are Photoshop compatible plug-ins available that add this functionality. A good one can be found at : It should work with every software that accepts Photoshop plug-ins Adjusting curves directly in the photo With Photoshop CS4 you have the option to adjust the curves directly within the photo. After opening the adjustment level for curves, you can see an icon with a hand in the upper left of the toolbox. Click on it to activate it. Now go with your mouse into your photo and click into an area you want to make lighter or darker. Hold the left mouse button and move your mouse up to brighten that part, or down to darken it. In the toolbox you can see how your curve is changed. Imho working directly with the curve gives you more control, but for quick adjustments that is a very great option to have

21 tool for direct adjustment of the curve from within the photo 2.5 adjusting colour Next thing we need to do is to make the colours a little more intense. For that we create an adjustment layer for hue / saturation. This is done the same way, as the other adjustment layers. If you tick the preview box in the settings dialogue you can see the chances in real time. I advise to be very careful with those settings. Many cameras, especially smaller compact ones, are already using quite saturated colours from the in-camera processing

22 Settings for adjustment layer hue / saturation I did like the colours, so only a small adjustment was needed. If you are fighting a nasty colorcast in your photo that makes it look to blue, red or green overall, you can try a different approach. Select that background layer where your original photo is located. Go to Image -> Adjustment -> Match Color. In the following dialogue box check the neutralize control box and click ok. It often helps to remove a colorcast. CS4 adds the vibrance adjustment layer. There you can add vibrance to the photo as well as saturation. If you colours look a little dull, although you have adjusted the contrast correctly by using levels and curves, it is a good idea to add some vibrance (up to +20) and a little saturation. 2.6 brightness and contrast If you are not fully satisfied with the contrast even after using the curves function, you can use an adjustment layer for brightness / Contrast. As you have already worked with the curves function, you should only need very minor adjustments using this tool. If you still need to make strong adjustments it makes more sense to work with curves again

23 Settings for the brightness / contrast tool 2.7 done with the first adjustments If you are happy with the contrast, the colours and the brightness it is time to move on and make the photo ready for upload to the aviation databases on the internet. For that we have to flatten the image. Go to Layer > Flatten Image and all the adjustment layers will be applied to the background original. From now on you can not work on the levels or the curves anymore. 2.8 reduce noise If you feel your photos it too noisy, it is a good time to put it through a noise filter now. You can use the filter that comes with Photoshop or filter like neatimage. But be careful with the settings; do not create a loss of detail. For the filter that comes with PS CS2 I prefer to use the following settings. Strength: 5 Preserve Detail: 100 % Reduce Colour Noise : 20% Sharpen Detail: 0 % Remove jpg artefacts: not checked

24 Using noise filter General Advice: This is an optional step 2.9 Resize For uploading the image to the internet database we have to resize the image to fit the needs of the database. The most typical size is 1024 px (pixel) wide, so we will use this in this example. Go to Image -> Image Size and open the dialogue Check scale styles + constrain proportions + resample image (bicubic)

25 Settings for resizing your photo to 1024 px wide 2.10 remove dust spots The next part is to get rid of any dust spots that have found their way onto your cameras sensor and into the photo. For that we will first duplicate the background layer. For that you go to the Layer toolbox, right click on the background layer and click on duplicate layer in the context menu. A dialogue will appear that asks for a a name of the new layer, Background copy is just fine for us. The next step is to select the background copy layer

26 Duplicating a layer Then go to Image -> Adjustments -> Equalize In our example we see a spot slightly right over the tailfin

27 After equalizing the background layer Now you need to select the background layer again. Then you zoom in on the spot and select the clone stamp tool. I use the following settings for the Clone Stamp Tool. I use a soft brush, Mode = normal, Opacity = 100%, Flow = 100%, Aligned checked, Sample all Layer not checked (IMPORTANT) You look for a piece of sky that is similar to the one were you want to remove the spot. You hold down Alt and left click on that part of sky. Then you release Alt and left click on the spot. Do not be surprised if it does not disappear. It has to be so, as we are removing it on the background layer, which is hidden by the equalized background copy. Remove all spots that way. Another option is to use the Repair Brush Tool, for that. It works exactly the same

28 Using clone stamp tool After you are certain you have found all spots and removed them on the background layer. You go to the Layer toolbox and right click on the background copy and then select delete layer. You can copy and equalize the background again just to be 100% sure you got all spots basic sharpening You can use Unsharp Mask for your editing. Go to Filter -> Sharpen -> Unsharp Mask I would start with the following settings: Amount : 50 Radius : 0,4 Threshold : 0 After 3-4 times of using these settings the first jaggies should appear, then you have to undo the final step

29 Sharpening using Unsharp mask Another option is to use the smart sharpen function. Go to Filter -> Sharpen -> Smart Sharpen I use 2 settings for my needs. I start with a pass using the following settings : (basic settings selected) Amount: 55 Radius: 0,5 Remove: Gaussian Blur More Accurate: not checked For the following passes (mostly only one more is needed) Amount: 40 Radius: 0,1 or 0,2 Remove: Gaussian Blur More Accurate: not checked

30 Using Smart Sharpen Again you keep repeating until jaggies appear and then undo the last step advanced sharpening If you have done the basic sharpening and find that some parts of the aircraft are still soft, while others are already over sharp you will need to take a more subtle approach on sharpening. You undo your sharpening steps from the basic way until the part that is the sharpest is perfect and has no jaggies. Then you duplicate the background layer. (See removing dust spots). This time you do not equalize the layer. Instead you select the duplicated layer and keep on sharpening until the rest of the plane is sharp as well. This will have created jaggies on the parts that were sharp already. Then you select the eraser and erase all the parts that have jaggies from the background copy layer

31 Removing jaggies with the eraser tool When the overall photo looks perfect, you go to Layer -> Flatten Image Advanced sharpening technique to reduce noise in the sky If you have taken a shot at higher ISO it might be a good idea to use the magic want tool to exclude the sky from sharpening. Select the magic wand tool by activating the correct selection tool. (it looks like a magic wand) Then you click onto the sky. The tool will now select all pixels of a similar colour. To control what pixels are selected you can change the tolerance of the tool. More tolerance means that more pixels will be selected, as the difference between the pixels can be greater. If the first try does not select he whole sky, you can switch the tool to the add to selection mode and select pixels outside the currently selected area until you have the whole sky selected. If the selection also grabs parts of the aircraft undo the last step and decrease the settings for tolerance. After you have selected the whole sky, go to the Select pull down menu and click on inverse. Then duplicate the background layer and add a layer mask. The selection will be removed. But that is no problem in the layer toolbox you see a new layer mask thumbnail for the copy of your background layer. Hold down CTRL and left click on it. The selection is back. But as we have created a layer mask we do not need to have a selection. Just do the sharpening on the background copy layer. When you are satisfied merge the two layers again. Now you have only sharpened the plane. Under most circumstances this method is not needed. If you use it be very careful that you are doing the selection correctly and check

32 the final result for any visible part of forgot, or any artefacts you might have created. Equalizing the layer is a good idea to be save. Selection of sky Layer mask created

33 2.13 Saving the photo for upload Go to File -> Save As and give the edited photo a new and unique name and selected Format : JPEG from the pull down menu. (it should be selected automatically). Click Save and it brings up the JPEG options dialogue. Set Quality to 12 Maximum Format Options : baseline (Standdard) Click ok. Saving your photo for upload. After you have saved the photo, you only need to upload it to the website

34 Edited version of the example 3. Editing Tricks 3.1 Shadow and Highlight tool Under Image -> Adjustment -> Shadow / Highlight you will find a tool in Photoshop that can be used to correct exposure. However it has some bad side effects. It can create halos around parts of the aircraft or the background. I have used the example photo and made the changes we did with levels and curves with this tool. To make it more obvious I have equalized the photo after that

35 artefacts from using shadow and highlight tool You can clearly see the dark halo along the upper fuselage and around the tail. Most websites will reject a photo that has such halos. General Advice : Do not use the Shadow / Highlight Tool 3.2 Lens Correction filter If you have problems with vignetting or purple fringing PS CS4 offers the Lens Correction filter which can be found under Filter -> Distort -> Lens correction. It offers an easy way to reduce vignetting or purple fringing. As the best settings are fully dependent on lens you use, you have to work out the best solution for your camera and lens. Always be careful not to overuse the filter and create manipulation artefacts, which will mean that your photo will be rejected by most websites. Rather leave some vignetting, than overdo the correction and make the corners brighter than the centre

36 Lens correction filter dialogue 3.3 Useful Photoshop shortcuts Ctrl+Z Ctrl+Alt+Z Ctrl +A Ctrl+C Shift+Ctrl+I Ctrl+F - undo last editing step - undo editing steps one by one - select all - copy selection - inverse selection - use same filter settings again 4. Setting up the camera for easier editing 4.1 File Format RAW or JPG is the basic question here. RAW data is direct sensor output data, that has only seen none or very little adjustemnts in camera. It gives you the option to change many parameters without quality loss after taking the photo. You can easily adjust the exposure

37 (add exposure compensation) or change the whitebalance setting. It is also no problem to add noise reduction or add sharpening, saturation or other image parameters as needed. RAW also gives you the best possible base to work from. The JPGs given by the same camera are often not of equally could quality. Especially with an older DSLR RAW makes the last reserves of image quality available to you. But RAW also has its drawbacks. The files are much bigger than JPGs, so you will neeed more storage space. Some cameras will fill up their buffer faster in RAW and the burst speed (frames per second) can be reduced. Additionally RAW means an additional step in editing. The RAW file needs to be converted to a different format, before you can start the editing. I would suggesdt to use a lossless fromat like TIFF or BMP, although the files will be huge. You can convert into jpg as well, but you must remember that opening and saving a jpg reduces the quality of the data. You should do all editing in a copy of the original jpg. Adobe Photoshop and other editing software can be used to open and convert RAW files from most common cameras. During the conversion it gives you the option to change various image settings. (WB etc.) Most camera amkers also supply a software that allows conversion of such files. For some makers there are free versions of the software others have free and commercial versions. I would usually stick with the free version. If you use Adobe RAW or the RAW converterter delivered wit the camera is up to you. I suggest trying both and use which you like more. As you see shooting RAW has some clear advantages, so should you use RAW every time? There is no general answer to that. Some say yes others no. I suggest to use RAW when you are shooting something that is important. Be it important to you or to the customer. If the motive is not important and you could come back and try another day, then I use JPG. JPG are less forgiving on wrong camera settings, which makes me learn the camera much better. 4.2 Important for shooting JPG As JPG depends much more strongly on correct in camera settings there are few things you should nconsider: In camera sharpening needs to be set to a low setting. Sharpening artifacts created in camera and contained in the original out of camera JPG can not be removed in editing Colours should not be too saturated. It es easier to add satruration in editing, than correcting an over saturated image. In camera tools for optimizing exposure (for example Nikon D-Lighting) should be turned off. If you use RAW you must know how your camera handles the white balances. On todays camera the automatic whitebalance will usually work ok under natural light, but once you go into buildings or try night shots it is likely that the colours will not be correct. If you do not want to use RAW in that cases you should know how to change whitebalance presets and how to take a manual preset