• Loading image of sizes >2000×2000 causes the software to stall (fixed, but still impractical for processing).
• Changing the color channels after processing causes messed up data in the Output tab.
• Summary in the Output tab isn’t updated when manually select/deselect objects.
• Some image processing tools in the Tools tab don’t work properly.

• Your choice of settings in the Output tab (the position of the sliders) is preserved when you load a new image to analyze.
• Your choice of color channels in the Analysis tab is preserved when you load a new image to analyze. With these two the user can apply the same settings to a sequence of images if they are similar in nature. So, we get as close as possible to bulk processing without actually creating this complex feature.
• Luminosity is a new color channel that you can choose. It is computed as a combination of the red, green, and blue values: 0.299*R + 0.587*G + 0.114*B. There are four channels now.
• “Display channel” is a new option in the Analysis tab (just like the one in the Output tab). If you have chosen to shrink the image, the shrunken version is shown. This way you can preview all channels and decide which is the best – before committing to time consuming analysis.
• The “Help” menu provides now the links to the help pages of this wiki. The user’s guide and the license are still provided with the program; they are to be found in the “Pixcavator” folder on your hard disk.
• The actual processing time is shown when it’s done, and a beep is produced – but only if processing has taken more than 5 seconds.
• Up to 2000 contours are now shown on the image and their statistics is also displayed. When there are more than 2000 contours, neither is shown.
• A few bugs have been fixed, some remain.

Download here.

It is a single file “exe” program that does not require any installation. As such it can be used as an alternative to screenshots, for demos etc.

This edition has all the features of the standard edition except for image processing tools. This way you can choose different color channels for your analysis, experiment with the sliders, and save your work.

Most of image analysis examples will soon have links to the corresponding files. For a start, try to run these two examples:

• immunohistochemistry,
• melanoma.

In FF: choose “Save”, then “Run”. In IE: just choose “Run”.

We will also be able to create such files as a service to our customers.

These reports are based on the data in Pixcavator’s output table that lists all objects in the image as well as their  measurements and locations. The table, combined with the analysis settings, the statistical summary, and the frequencies of the values in the table, can be saved to hard disk in the form of a spreadsheet. This spreadsheet is a complete report of what has happened.

The frequencies allow one to create a histogram for each column, such as the size, to graphically illustrate the distribution of the values. One can also add images, format the text, etc. The end result may look like this:

For more details read Report generation in the wiki.

A note to our current customers: If you purchased Pixcavator within the last 12 months, i.e., after December 13, 2008, you are entitled to a free upgrade. You can download the new version here and then activate it with your current activation number. If your purchase dates before December 13, 2008, you can acquire the new version here. It goes without saying that the older versions of Pixcavator are to remain active indefinitely.

In the late December the price of Pixcavator will be increased to $245.

From other news, our site Computer Vision Primer has reached 268 articles with over 780 illustrations. The fastest growing category is image analysis examples which has reached 56.

Besides a few minor improvements, the main novelty is more ways to change the analysis settings. There are six sliders now.

As before we have two sliders for the two main measurements – size and contrast. Now, the confusingly named “Max growth rate” has been remade into “Border contrast”. What does it mean? Both this and the second slider consider the difference in intensity inside the object from that of the surrounding area. But, while the contrast slider considers the maximal difference throughout the object (that why it’s now called Max contrast), the border contrast slider looks at the area just inside the contour. The result is about the same as before: it detects sharp edges, i.e. the contours with the largest difference between what’s just inside and what’s just onside of it.

The next slider works similarly but takes into account the average difference in intensity inside the object from that of the surrounding area. It’s called Average contrast.

The last two sliders simply threshold the image. For example, if you set Intensity, dark to 100, the contours of dark objects will the intensity equal to exactly 100. If you set Intensity, light to 100, the contours of light objects will the intensity equal to exactly 155 (here 155=255-100). It was set this way in order to ensure that contours grow as you move any of the six sliders from left to right. This is a very unsophisticated tool but it’s quite effective when the image lighting is uniform.

The need for introducing these new tools came from a specific, real life image analysis task: Measuring staining in the liver.

Reminder to the current customers: you can download the new version and activate it with your current serial number.

Reminder to the rest: the new price $195 won’t become effective until June 15.

After a few minutes of experimenting with Pixcavator, this is best I can do for now (screenshot #1 below). As you can see some of the red area is not captured while some holes are counted (#2). To find area of those holes I had to analyze the image with different settings (#3). So, the total area of the red is approximately:

10864+3501+1426+2103+1746-1477-1453 = 16710.

Then the percentage is

16710/(853×640) = 3%.

Unsatisfied with the result, I modified the software: I used thresholding as the 2nd slider instead of contrast and redid the analysis. The result was 5.51-1.65=3.86%, much better. 

The third image was trickier because the lighting is uneven. Initially I was unable to capture all brown areas – not simultaneously. Certainly, cropping the image and analyzing parts one by one is an option. (The average color, it is displayed for each contour under “Gray” in the Pixcavator’s output table). That’s something to keep in mind: what is displayed is the average intensity with respect to the color channel that you’ve chosen, in this case “Green”. (The ability to compute the average color with respect to all three channels is still under development.)

Unsatisfied with the result, I came up with another modification: I used average contrast for the 2nd slider and redid the analysis. The result was much better. The average gray (intensity in the green channel) was 132.

The two modifications will appear in version 4.2 due in June.

The main changes in this version of Pixcavator are the following.

First, an annoying bug in the user interface was fixed. I don’t want to remind everybody what it was but I do certainly apologize. A few minor bugs were fixed too.

Second, a new slider “Border contrast” replaces the old. The idea is that by moving it you can jump to the nest sharp border. For example in the image below, the change in the gray level is very gradual. So, if you move the slider “Size” or “Contrast”, the growth is very slow and the former won’t even notice the sharp edge. With the new slider you get there is just a few abrupt steps: border contrast = 0, 10, and 15, respectively.

To our current customers. You can download the new version of Pixcavator and then activate it with your current serial number. This amounts to free upgrades for a foreseeable future.

BTW, the first digit in the version number refers to the calendar year of the development. This is the fourth since version 1.0 appeared in August ’06 (a prototype/testing program was created in the summer of ’05).

Finally our plans for the coming months:

• 4.1: Introduce a way to fully pre-compute all data (not only the construction of the topology graph but also and its analysis) so that moving sliders will change both the contours and the sliders virtually instantly.
• 4.2: Speed up the core algorithm (construction of the topology graph) significantly. I think its complexity will be linear instead of the current quadratic.
• 4.3: Introduce more data filtering tools (beyond unmark dark and light objects).

I’d be glad to hear your suggestions.