kinect depth image thresholding

i have got depth image of the table. i want a fixed depth(in number) so that i can perform comparison with the depth of my finger tip. i have extracted co-ordinates of fingertip and depth also. but mismatch occurs due to depth variation of kinect. below figures are attached having different depths in same image. kinect changes its depth with addition of 4. if one pixel has depth of 1175 then some distant pixel has depth 1179. can anyone help even i cant get regions of same depth in the depth image.

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[KALYAN ACHARJYA]

What you are representing here by depth? is it Pixel depth? your e.g 1179..

[subhash kumar]

it is the distance between kinect and the flat surface(table)

[subhash kumar]

white pixels have the depth titled on the image.

[Image Analyst]

Can you attach your two images, like in a .mat file?

[subhash kumar]

dataa.mat contains depth and rgb image

Answer 1

[Image Analyst]

From the RGB image, it looks like it's looking at a flat computer screen. And since that's mostly flat it makes sense that there would not be much dynamic range in the depth image. As to why there are the vertical artifact in it, I do not know.

% Demo by Image Analyst.
% Initialization steps.
clc;    % Clear the command window.
fprintf('Beginning to run %s.m ...\n', mfilename);

Beginning to run LiveEditorEvaluationHelperEeditorId.m ...

close all;  % Close all figures (except those of imtool.)
clearvars;
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;
s = load('kinect dataa.mat')

s = struct with fields:
    d1: [187x339 uint16]
    r1: [187x339x3 uint8]

depths = s.d1;
rgbImage = s.r1;
subplot(2, 1, 1);
imshow(rgbImage, []);
impixelinfo; % Let user mouse around and see values displayed on the figure.
title('RGB Color Image')
subplot(2, 1, 2);
imshow(depths, []);
impixelinfo; % Let user mouse around and see values displayed on the figure.
title('Depth Image')