Python ImageStat Module

Quiz

Using the ImageStat module, statistical information of the image or the part of image can be calculated once after image is loaded.

Information like total number of pixels of image, sum of all the pixels, mean, standard deviation, variance etc. can be calculated using this ImageStat module.

In general, the statistics of the image are mostly used by data analysts, scientists and researchers who are interested in understanding how to compute in the context of image processing, or in any algorithm aiming at producing natural languages ImageStat modules contains a single function Stat

Functions

ImageStat.Stat(image) => Stat instance

Creates a ImageStat instance with which you will be able to retreive various information

Attributes : In order to retrieve the statistics of the given, first image has to be loaded with Image class and create a ImageStat object by passing the Image object as the argument.Now call the ImageStat object with various attributes

Attribute name	Description
extrema	Min/max values for each band in the image
count	Total number of pixels for each band in the image.
sum	Sum of all pixels for each band in the image..
sum2	Squared sum of all pixels for each band in the image.
mean	Average (arithmetic mean) pixel level for each band in the image.
median	Median pixel level for each band in the image.
rms	RMS (root-mean-square) for each band in the image.
var	Variance for each band in the image.
stddev	Standard deviation for each band in the image.

Below example program displays various metrics of the image.

from PIL import ImageStat,Image
# Loading the image object
img_obj = Image.open("image1.jpg")
# Creating ImageStat object by passing Image object
stat = ImageStat.Stat(img_obj)
print "Number of pixels     :", stat.count
print "Min/max values for each band in the image",stat.extrema
print "Get sum of all pixels:",stat.sum
print "Average pixel level  :",stat.mean
print "Median pixel level   :",stat.median
print "Root-Mean-Square     :",stat.rms
print "Variance             :",stat.var
print "Standard deviation   :",stat.stddev

Output:

Number of pixels     :[50400, 50400, 50400]
Min/max values for each band in the image [(0, 255), (35, 255), (0, 255)]
Get sum of all pixels:[8183620.0, 9138785.0, 4436852.0]
Average pixel level :[162.3734126984127, 181.3250992063492, 88.03277777777778]
Median pixel level  :[204, 201, 18]
Root-Mean-Square :[185.51091612085798, 191.09265656444558, 133.23823498495003]
Variance          :[8049.17484867095, 3637.611790664759, 10002.657298633158]
Standard deviation:[89.71719371821072, 60.312617176381586, 100.01328561062854]

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