There are strict guidelines on what pictures are suitable for use on a passport, and getting this right can be expensive with photo machines charging a high price for a sheet of correctly sized images. It is possible to take your own passport photographs at home, provided you adhere to the necessary guidelines to ensure the photograph is suitable.
Take a photo with a digital camera. The room needs to be naturally lit if possible, as photos that are too light or too dark will not be accepted. Leave the flash off, and allow your camera to use standard exposure settings. The person you are photographing needs to in the middle of the photo at the bottom, with the photograph ending around their chest. The background should be plain or off-white.
Measure the distance between the person's chin and the top of their head. This should be between 1 and 1 3/8 inches. You may be able to measure this using graphic software, or simply measure using a ruler. It is advisable to aim for around 1.1 inches.
Crop the photograph so that it measures 2x2 inches. Most graphic programs will offer the ability to crop to a fixed size. Ensure the person's nose is at the centre of the image when it is cropped.
Copy the image by right-clicking and select "Copy."
Open a new image, setting the size to 4x6 inches.
Paste your image into the new window by right-clicking and pressing "Paste."
Move the image to be in the centre of the new window. You will be able to fit a second image underneath. When these are correctly positioned, save the document.
Print the document onto high quality printing paper, or send the document to a professional printing company. Inform them that they will be used as passport photographs, to ensure the company does not resize the images.
If you are not comfortable using graphic software, you can print the photo and measure with a ruler, scanning it back in when necessary. Scan on your highest setting so that the quality of the picture remains high.
Always check your country's photograph guidelines. While America is happy to accept home-printed pictures that meet the guidelines, some countries require a professional passport photograph.