The Blob Tool is for counting and sizing objects.
This involves thresholding the image, distinguishing objects from background, using Menu Bar / Colorize / Threshold Slider. Briefly, you click on an open image to bring it in front, then use Blob Tool / Blob Image / Use Front Image to select the front image as the one to be "blobbed". Then, use Blob Tool / Blob / Blob to actually blob the image. Here are examples, giving detailed steps: Potato (single large particle), Small Particle Count . More details are here.
Blob Buttons & Menus
Drawing Buttons and Commands
Measurements from a folder of images.
Blobbing without Thresholds
Super Blobber Journal Article
Blob or Particle Statistics
List of blob statistics, or measurements
Stats button commands.
Example of outlines of small particles:
This color scheme is out of date, but the blobing functions have remained largely the same.
The blobbing operation collects and labels contiguous groups of red pixels (chosen with the threshold slider). For example, to size particles, set the threshold so that the particles are red, then use the blob button. ( How to segment an image into blobs.) Blobs are stored as their outlines in binary files, which are not meant for export to other programs.
This tool segments an image using a ‘super blobbing’ algorithm, which does not require you to choose a threshold. The algorithm blobs an image starting at the minimum image intensity, and increasing the threshold by a threshold increment. The first blob - the entire image, is gradually split into smaller pieces. See html paper about the algorithm for more details. (The threshold slider is not used or needed for super blobbing.)
The graphics drawn by the Blob Tool is not permanent – it disappears when the image is redrawn (R button) or covered by another window and then uncovered. The P button redraws the blob perimeters in different colors and the L button redraws the labels. The Draw button is a menu for drawing various things such as convex hull, perimeters all in one color, diameters, etc.
Explanation of .
Three buttons select the images on which the blob tool works. All three buttons can select the same image - normally this is the case. Sometimes, however, you may want to to draw blob outlines from one image on another image, or use the intensity information from one image and the blob outlines from a second image to get brightness statistics.
The exclude list has blobs that are mostly ignored. All other blobs are outlined, labeled, and in the table of statistics. All non-excluded blobs are called 'good' blobs. The select list has blobs that are selected for special purposes. Only good blobs can be selected. Most operations work on all good blobs. Some also work on selected blobs only, such as: drawing outlines listing statistics showing spectra in PPP window transferring selections to spreadsheet.