Macro photography under Linux

Masked Ball

Users experienced in image processing will probably like to use the --save-masks and --load-masks in enfuse . The first of these generates two masks in the work directory for every image file that has been read in and processed. These two masks include hardmask-<Number> and softmask-<Number> .

The soft masks are generated automatically. The hard masks appear with the --hard-mask option. These masks contain masks that are constructed with the algorithm referred to above and which detect the sharp regions of an image. --hard-mask also lets you use the hard masks for merging images. Figure 10 shows a mask like this. The white regions are used by the underlying image during merging. The black regions are discarded.

Figure 10: This is how the masks generated in enfuse using the --save-masks option look. They can be loaded in Gimp and manually processed.

Soft masks are always generated by default in enfuse as softmask*.tif . They contain soft transitions between individual images. They are therefore gray stage images in contrast to the black and white hard masks.

These masks are intended for the overlay of high resolution HDR images and are only suitable for the tasks lying ahead of them in focus stacking if they have been thoroughly processed, for example with the curve tool. Usually, you will get better results more quickly with the hard masks than with the soft ones.

There are two possibilities for using these masks. To do so, you should load them in Gimp so that you can then modify them with a paint tool (for example, you could use either a soft pencil or a hard brush). You could also even think about using the calligraphy tool, which would let you generate very hard edges in the mask. Next, you should write over the original version with the modified mask and use it with --load-masks .

Alternatively, you could use the masks directly in Gimp. This involves a somewhat advanced technique that also offers interesting possibilities. To get started, you should load the image belonging to the mask, for example align0001.tif . You should prepare this image by adding a layer mask by clicking on the Layer menu and then Mask and Add layer mask .

Next load the mask as an additional layer using the Open as layer … in the File menu. Then using Ctrl+X followed by Ctrl+V, you can cut this layer out and add it to the clipboard and also as a floating selection in the image. You then add it to the layer mask with Anchor layer in the Layer menu (Ctrl+H).

Now you will see the effect that the mask has (Figure 11). You can modify this mask manually and immediately observe the effect. One thing to note here is that you might want to see exactly one layer at a time during processing. Clicking on the eye of the layer in the layer dock while holding the Return key lets you temporarily turn off visibility for all other layers.

Figure 11: You can use hard masks in Gimp as layer masks.

It can be essential with hard masks to create certain transitions in order to achieve realistic results. This is accomplished with Gimp by first loading the mask as a standard image. Then you should select all of the white regions with the global color selection, extending the selection via enlarge … and hide from the Selection menu. Next fill the new selection with white. The outcome will be a somewhat larger selection with slightly softer edges with which you can then soften the transitions.

Reworking an Image

The Processing button in MacroFusion starts the image processor you have specified in the Configuration tab under Edit with . Most of the time, this will be Gimp. Frequently, it will be necessary to rework the images that have been generated. Figure 12 illustrates a typical problem. The very good output images and the use of the layer mode "hard edges" for combining the layers are responsible for the excellent sharpness of this image. However, this leads to colored artifacts that subsequently need to be edited, for example by removing the colors, adapting to color temperature, etc.

Figure 12: Some typical problems are shown here. The artifacts at the lower edge of the screen need to be removed manually. These are not present in all of the input files. The color errors are also in need of correction.