I am trying to learn the internals of image file formats and I wonder whether there is an application that could explain a file byte by byte.

I am thinking of something like Wireshark which actually has built-in suppport for PNGs. I especially like the UI of Wireshark, where data is grouped and can be expanded for more details and it highlights the raw bytes associated with the currently selected item (see screenshot below where the mouse hovers over "textual data").

The software should be gratis and for Windows. It should support all major images file formats: at least PNG, JPG, BMP, TIFF and GIF.

Ideally it would display the image, allow editing the bytes directly and update the preview immediately when changes are made.

Wireshark analysis of a PNG file

1 Answer 1


The SweetScape 010 Editor is an hexadecimal editor that has optional support to represent the data in a view of properties/fields with the associated bytes to that field, I think tsomething like this is what you are looking for.

enter image description here

To represent the specifications of one kind of file, you need a specific plugin/template for that filetype, the program comes with very few templates including Bitmap (.bmp), but you can download a lot more templates for image fileformats in their website:

Also, as you can see templates are just plain textfiles with struct definitions and a little bit of what seems Visual C++ code (I'm not sure about), so any user with basic knowledges of that language and knowing the specifications of the desired fileformat can extend the templates in a easy manner for a big amount of file formats.

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    +1, although it's not gratis (50 USD for home use, 130 USD for commercial). I appreciate the answer. Maybe I should consider removing the gratis tag Feb 16, 2016 at 13:58

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