Simple trick to add zip file to jpg image

Sometimes I have a PCB (printed circuit board) to realize. Usually, I send my design to local (italian) producers, but recently I’ve seen on a famous internet shop (four letters, starting with ‘e’ ending with ‘y’) some advertise from chinese producers, giving the PCB service at VERY low price. My PCB design files are always in GERBER format, with all sections shrinked in a single zip file.

If you decide to send your design to such chinese producers, generally you must mail your zipped gerber to the factory using your private email, ‘cause the “famous internet shop” only accepts jpg files as attachments in messages from buyer to seller (or viceversa).

This limit gaves me an idea : to create a jpg file that has a image part (my logo, for example) and hidden embedded gerber file. This way, I can send the data using the mail messaging offered by “the famous internet shop” without the need to use my private email account.

The procedure to create such embedded jpg is VERY simple:

a) put the (or ANY OTHER zip file) and the “container” image.jpg on a temp folder…

b) open a “dos command” window, navigate to the temp folder, then type: copy /b image.jpg + miximage.jpg (I usually create a batch file with this command in that folder,)

This command creates a copy (binary copy, thanks to the /b option) of the jpg PLUS the zip file. Now, if you open the resultant miximage.jpg with an image viewer, you will see the “container” image, but if you right click on the same jpg file, choosing “open with”, and selecting the application 7zFM.exe (from folder 7-Zip, under program files), you will discover that all your zip file contents are also present. The link to 7Z, my favourite zip/unzip application, is on the right side of this page, under useful links.

With this “mixed” file, you can use the mail message system of the “famous internet shop” to send your data to the chinese factory, attaching to your message the embedded jpg file. This is good for avoiding to use your private email and for have a seller-buyer transaction covered by the payment protections of the shop.

Hope this will be useful for someone…