How does php convert some fields received by the form into images for saving?

Some fields received by the form, such as the QQ number or something, are saved in the database after receiving them and converted into an image to save them. Is there any toolkit or something like that? Some fields received by the form, such as the QQ number or something, are saved in the database after receiving them and converted into an image to save them. Is there any toolkit or something like that?

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Some fields received by the form, such as the QQ number or something, are saved in the database after receiving them and converted into an image to save them. Is there any toolkit or something like that?

You need to check the php GD library, which is very easy

Is the number directly written to the image? If so, the implementation principle is the same as the verification code. If the encoding is used to generate an image, I 'd like to know about it. The subject successfully told me about it.