What use is Capture NX?

Capture NX 2 is Nikon's high end RAW converter. It opens NEF, JPEG and TIFF files and also saves in those formats. It has many more adjustment options than View NX, and it can add and remove them in a way that is similar to Adobe Photoshop's adjustment layers.

The most unique feature of Capture NX is probably the "Control Points" that let you easily make adjustments to areas of the picture that are similar.

When it comes to high end RAW converters, like Capture NX, Adobe Camera RAW, Adobe Lightroom and Apple's Aperture, they all have their strengths. It is very difficult to tell which one is "best". Someone who masters any one of them, can usually do what s/he needs to do with that program. Anyone who does not fully master any one of them will probably not achieve the best possible result.

Capture NX is not an image editing program. You cannot use it to paste a face from one person onto another. Neither can you render patterns or add text strings to a picture. For such tasks, you need to use a tool like Adobe Photoshop or the gimp.

Capture NX can perform batch jobs on several pictures at once. However, it is not scriptable with any internal macros or AppleScript.

Chromatic Aberration

Chromatic aberration is a consequence of the fact that light of different colours do not focus on the same plane when they go through glass. Think of a simple prism, where white light goes in and a rainbow of colours come out.

Camera lenses are not always good at compensating for this, and the result may be a blue thin line around objects.

To get rid of the line semi-automatically, you can use tools like:

• Adobe Photoshop - Filter > Distort > Lens Correction. Adjust the slides in the box "Chromatic Aberration".
• Adobe Camera Raw - Open the file. (If it is not a raw file, you right-click on it in Bridge and select "Open in Camera Raw..."). Click on Lens Correction. Adjust the slides in the box "Chromatic Aberration".
• Capture NX - In the Edit List, click on "New Step". Select Adjustment > Correct > Color Aberration Control.

You can also manually replace the colour using things like the "Hue and Saturation" adjustment in Photoshop or the Gimp. In Photoshop you can also use Image > Adjustments > Replace Color.

If you do not succeed in getting rid of the chromatic aberration, do not feel bad about it. It is a tricky thing to handle. Good software takes into account the camera and the lens. As an example, Canon's RAW editing software Digital Photo Professional does not make the Chromatic Aberration correction tool available for pictures taken with the Canon EOS D20. Neither does it attempt to correct TIFF or JPEG pictures. This is undoubtedly because Canon knows they cannot make good enough corrections for those pictures.

Wikipedia has a more information on the subject.


The Lens Correction tab in Adobe Camera Raw.


Example of a picture with both green and red chromatic aberration.

Detail showing red aberration on one of the birds.

Detail showing green aberration on another of the birds.

HDR with the gimp

Basic HDR can be handled in for example the gimp.

We start off with this image:



The areas where the leaves are in the shadow are underexposed, so no details are visible. The sand in the foreground is overexposed, so hardly any details are visible. It would be very difficult to find a setting where the camera captured everything correctly.

Luckily two other pictures were taken at the same time. One was had a longer shutter speed, so it is even more overexposed:



The other picture had a shorter shutter speed, so it was more underexposed:



The trick is to use the good parts of the overexposed pictures and the good ones from the underexposed picture and put them together with the good bits of the original picture.

1. Open all three pictures in the gimp.
2. Copy the underexposed picture, and paste it as a new layer on top of the original. (Click on the underexposed picture > ctrl+A > ctrl+C > click on original > ctrl-L to display the layers > click on the New layer icon.)
3. Copy the overexposed picture, and paste it as a new layer on top of the original. (Click on the overexposed picture > ctrl+A > ctrl+C > click on original > display the layers > click on the New layer icon.)
4. Save the original image in a new xcf file, in case something goes wrong.



In the image above I have also renamed the two pasted layers.

We now want to hide the overexposed areas of the overexposed picture. To do this we use a layer mask.

5. Highlight the overexposed layer.
6. Go to the menu Layer > Mask > Add Layer Mask.
7. Select "Grayscale copy of layer" and "Invert mask".

We now want to hide the underexposed areas of the underexposed picture with another layer mask.

8. Highlight the underexposed layer.
9. Go to the menu Layer > Mask > Add Layer Mask.
10. Select "Grayscale copy of layer" but not "Invert mask".

We now have a picture where the sand no longer is overexposed and the leaves no longer are underexposed.



To change it further, we can apply curves to the layer masks, to fine tune which parts of the picture are hidden by the layer.

11. Click on a layer mask.
12. Menu Colors > curves.



Of course other changes, like increasing saturation can also be applied.