Carnoy is an application for measuring and analyzing images, especially those from microscopes. It is a rather specialised piece of software, targeted at professionals, like biologists and archaeologists. Its interface looks very clean and simple, designed with aesthetics in mind. However, being an absolute beginner in the field of measuring microscope images, it took me a while to understand its functions and to actually achieve any useful measurements. It appears that although its interface was created with care and the good intention of making it simple, it lacks some intuitiveness and its workflow is slightly confusing. Maybe professionals who are more acquainted with measuring images will find their way around Carnoy more easily, but I have some suggestions that I believe would make it much more intuitive.
The heart of Carnoy's interface is the toolbar, shown in Figure 1, a window that contains all functions that are used frequently. The two rows at the top of the window contain tools for measuring, navigating and calibrating, as well other often-used commands. Unfortunately, this toolbar is one of Carnoy's weaknesses. I found the buttons to be almost counter-productive, as there seem to be too many of them, with very different roles and behaviours. The colouring is meant to help distinguish between tools, which stay selected after clicking, and commands, which result in a reaction when clicked. I think the number of buttons should be cut down to only the most essential ones, and tools should be separated from commands using spacing. Also, some of the icons don't convey their meaning very well. Figure 2 shows a possible redesign of the Carnoy toolbar.
I chose to leave out the Open command, because it is not directly associated with the current image, unlike the other tools. The buttons for setting the scale and for one-click calibration are replaced with a single one, which is further explained below. I moved the button for storing a measurement to the button bar below the list of measurements, because I think it's more appropriate there. The Remove Measurement button replaces the Undo Measurement and Clear All buttons.
In order to carry out any useful measurements, an image must be calibrated, so that Carnoy knows how many pixels in the image correspond to a unit of length. There are currently three methods of calibration. One method is to draw a line of a known length on the image, click the "set scale" button and tell the application what that length is in real-world units. This assumes the user knows she has to draw a line before calibrating, although the button appears functional even if no line has been drawn. The second method can be used if the image has a scale bar. The user clicks the "one-click calibration" button, then clicks on a continuous area of the scale bar, which automatically selects it. She is then prompted to enter the actual length of the selected area. The third method involves manually entering magnifications in terms of the relationships between pixels and units in the preferences and then selecting one of those magnifications for an image after clicking the "set scale" button.
Understanding these calibration methods, and therefore using the application, absolutely requires you to read the documentation, which not every user will do, although the Read Me file suggests it. Making the way calibration works more obvious and providing more information in the interface could stop many users from turning away in frustration.
Since calibration is something that needs to be done only once for every image, I think a single button that offers the different methods in a dialog would be ideal. Figure 3 shows what this dialog might look like. It is a floating window and stays open while the user takes the necessary actions on the image. The toolbar window should be hidden or at least disabled while this dialog is shown, so that no other tools and commands can be used.
Currently, there is no indication of whether an image has been calibrated or not. Including this information in the toolbar would help the user a great deal at understanding Carnoy's workflow and how crucial calibration is.
Carnoy has a "threshold" feature, which basically turns the image into a black and white image based on a user-defined threshold in lightness. This feature can be easily accessed through the Threshold button in the toolbar, although I would slightly change its icon (Figure 2), which currently suggests a function for adjusting contrast. The dialog for setting the threshold is shown in Figure 4.
It is, for no obvious reason, a non-modal window, which has immediate effect and cannot be cancelled. This dialog should really be modal but movable, with an OK and a Cancel button. At the moment, it shows its effect only after you have changed the slider from its default value, but should actually do so immediately when opened. Also, when used after the first time, the slider should be set to the value that was last used. The Invert Image command, which is in the Edit menu and can be helpful when thresholding, could be implemented as a check box in the Threshold dialog.
There are other minor issues I found in the interface, which I'll just sum up here:
Carnoy has a very promising interface and was designed with some very important goals in mind. It looks and feels like a native Mac OS X application and is visually simple and uncluttered. Workflow and intuitiveness are now the most important issues that need to be worked on. It is very hard to design an interface that is intuitive to everybody if the author is used to doing things in a certain way. I hope that this article will give some insight into how a non-specialist sees the program and what they might expect from it.
Carnoy Product Information
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