PHP Logo

Steganography With Images In PHP

15th January 2021 - 18 minutes read time

Steganography is the practice of placing a secret message inside another message and only by looking at the original message in a different way can the hidden message be seen. This might be as mundane as writing a page of text and hiding a message in the text using the first letter of every sentence. Only by collecting the first letter of each sentence together can the hidden message be seen and read.

Modern steganography is defined as hiding a message (or file) inside a file. For example, you might look at an image and see an image, but if a message has been hidden you would also be able to extract it if you know where to look.

PHP Logo

PHP Script To Turn Image Into ASCII Text

6th October 2008 - 3 minutes read time

Use the following snippet to convert any jpeg image into the equivalent image in ASCII format. It works by loading an image using the PHP GD2 library function ImageCreateFromJpeg() and then figures out the height and width of it. It then uses these values to loop through every pixel in the image and figures out the colour of that pixel. It uses this value to create a "span" element that uses the text colour of a # to change the colour of the text.

An additional time (and space) saver for this function is that it detects any pixels that are just off white and simply displays a   character instead.

PHP Logo

Capture A Website As Image With PHP

7th April 2008 - 3 minutes read time

One thing that comes in useful when linking to other websites is to use a little thumbnail of the site as part of the link. Although it is possible to do this it usually involves having command line access to the server so that you can install various different programs and extensions.

The simplest mechanism accomplish this is to use third party sites to create the thumbnail for you. Here are a few examples of free thumbnail services.

Thumbshots provides access to small images (thumbnail size) of many different websites. However, they are very small, with no way to change this, and can often be weeks out of date if the site has had a redesign. You can access Thumbshots from any webpage by using an image with a source that reads from the Thumbshots website.