If you apply for UPSC Civil Services Exam through online mode, you have to upload two pictures of specified sizes.
The CSAT notification says:
Each of the scanned images of the photograph/signature should not exceed 40 KB in size (for photograph, the pixel size is 140 pixels height x110 pixels width and for sign it should be 110 pixels height x140 pixels width) and also to be ensured that the uploaded photograph/signature are proper.
For Passport sixe photo:
Get the passport size photo scanned or if you are getting a new photo then copy the photo in a new pen drive / CD from the Studio.
You have to sign on a white sheet (preferebly in black pen) and scan it.
The size of the scans will be above 40kb. So their size has to be reduced.
There are many ways to resize an image. Default MS paint program doesn’t provide some features, so for a hassle-free resizing, download and install Paintdotnet software (free) from following link. (size 3.5MB)
[You can also use gimp, adobe-photoshop, irfanview anything, the principle remains the same.]
Now open the image using paintdotnet.
Once you have resized the image, paintdotnet provides facility to save it with along with an option to change the image-quality so that it meets the 40 kb size restriction.
Still confusion in photo resizing and meeting the 40 kb size limit?
Then do as directed in following video (download size 600 kilobytes)
For signature, do as directed in following video (download size 300 kilobytes)