Blood analyser with out-of-focus image plane analysis and related methods

A blood analyser, the blood analyser comprising a memory, an interface, and one or more processors, the blood analyser being configured to:

• obtain image data of a prepared blood sample, the image data comprising data of a stack of images where each image of the stack of images is associated with an image plane, wherein each image plane is associated with a different height along a z-axis of the prepared blood sample;
• select a first image associated with a first image plane of the prepared blood sample from the image data;
• characterize the first image, wherein the characterization of the first image comprises determining a first set of cell regions belonging to the first image plane, wherein a cell region of the first set of cell regions is associated with a group of pixels in the first image representing one or more cells, a part of a cell, parts of cells, or an optical phenomena relating to one or more cells;
• select a first distal image associated with a first distal image plane on a distal side of the first image plane, and
• determine a first distal set of distal cell regions associated with the first set of cell regions, wherein a cell region of the first distal set of cell regions is associated with a group of pixels in the first distal image representing one or more cells, a part of a cell, parts of cells, or an optical phenomena relating to one or more cells, wherein the determination of the first distal set of distal cell regions comprises determining that the first set of cell regions do not belong to the first distal image plane;
• and
• determine a first cell parameter for each cell region of the first set of cell regions based on the first distal set of distal cell regions.