# '17-18 General Discussion for Lesson 2.3

I chose a B&W image from the submissions from 2.

For the third question in the â€śActivity Guide - B & W Pixelation Widgetâ€ť it asks â€śHow many bits would it take to represent the smallest possible image (i.e. an image with one pixel)?â€ť and after discussing the two previous questions, most of my students responded with â€ś3 bits - 2 for the 1 x 1 metadata grid size, and 1 for the image itselfâ€ť. The answer key says the answer is 17. But I was leaning with my students response, based on the question. Why do I need 16 bits for the metadata? If the grid is 1 x 1, with 1 bit for the image itself, could this not be represented using just 3 bits? MUST the metadata, regardless of grid size, be stated using 8 + 8 bits of information?

Short answer: Yes - according to the format given.

Because we donâ€™t know the image dimensions ahead of time, we have agreed to reserve the first 8 bits to communicate the width, then another 8 bits to represent the height. (And the rest is pixel data.) Thatâ€™s all we know ahead of time.

So letâ€™s say given this agreement, I try to read your 3-bit file. What would happen? (We wouldnâ€™t be able to interpret it following our rules.)

Does that also answer your question â€śWhy do I need 16 bits for the metadataâ€ť? If we agreed on 16 bits of metadata beforehand, I wonâ€™t be able to interpret anything you send me that doesnâ€™t follow that agreement.

Now, it IS possible to represent a 1-pixel image the way you describe, but we would have to change the image format - in other words, change our agreement on how we represent the data.

Maybe the question was phrased in a way itâ€™s unclear whether we get to change the formatting â€śprotocolâ€ť, but it seems if we interpret it to mean we get to change the format, thereâ€™d be no point in even setting aside pixels to communicate width and height if the image format you stated (1 bit for width, 1 bit for height) ever only allows an image to be 1x1 - if that were the case, you would only need 1 bit total to communicate pixel data.