how to get same image quality with bit depth after filter?

how to get same image quality with bit depth after filter?

if my input image 55Kb, output i want same 55kb, how can i get same quality ?

[KALYAN ACHARJYA]

Then why you use the filter? Quality means, size does not represent the quality of an image.

[Jan]

@Selva Karna: What are your input data? How do you measure the size of 55kB? Do you mean file size or data size? Is it a compressed file format? What does "with bit depth after filter" mean? Please post the code and clarify your question.

[Selva Karna]

clc clear close all [a,b]=uigetfile('*'); rgb=imread(a); %% rgb image [input image file size] 87kb Gray=rgb2gray(rgb); imwrite(Gray,'output.jpg') %% but output image size 71kb

so how can i get same size of image...? can you help me sir?

[KALYAN ACHARJYA]

rgb=imread(a); 
%%rgb image [input image file size] 87kb

First Image rgb is a color image, now you convert it to gray level image, how you expect the both should be the same size.

Gray=rgb2gray(rgb); 
imwrite(Gray,'output.jpg') 
%%but output image size 71kb

[Florian Morsch]

If you convert a image to grayscale you will loose some data, thats how it works. The result is a smaller image datawise, you cant prevent that and that data loss has nothing to do with quality change, its just your pixel turning from RGB to gray.