Can I turn off image compression?

[d4s_over_dt4]

I need to use images to store stuff for some reason,and if even a bit of them is corrupted,the whole message cannot decode.
How can I turn off image compression?

[bh]

Sorry. We might entertain that idea if we work out a way for you to pay for your own cloud storage (e.g., hooking your Snap! account up to your Drive or Dropbox account).

[joecooldoo]

You can maybe convert the image to a list and save it that way.

[sarpnt]

you could stuff a base64 url in an svg, but that takes up more than double the storage space of the original image, so please don't

if you're storing data, you should probably just store the data. i understand this is probably for the CTF you're trying to do but i don't think getting the pixels of an image is much of a challenge.

you could also just deal with the compression, and use something designed to deal with bad signal quality, or something where it doesn't matter too much. dial up, qr codes (or anything else on the wikipedia article for them), bar codes, anything digital will give an exact result. many analog signals should be fine as long as the output doesn't need to be exact, for example speech, various images, an image of written text, etc.

if this is something where multiple sprites have to be used with the image, such as a jigsaw puzzle, you can again use anything designed to deal with the compression. one interesting thought is a background that looks like random black and white, but when you put a qr code overlay on specific spots, it has useful information. maybe you can even block out another part inside the qr code, and get two different messages by manipulating the qr code error correction.

[d4s_over_dt4]

@sarpnt

i understand this is probably for the CTF you're trying to do

nice guessing

@sarpnt

i don't think getting the pixels of an image is much of a challenge.

I actually put the pics there just for storing the data,because putting a huge list reporter there is impractical,as the data is about 30000 8 bit numbers long!(i can't tell you exactly how many data,because you could do a prime factorization to crack one part of the flag challenge)

@sarpnt

you could also just deal with the compression, and use something designed to deal with bad signal quality

This is what I did in the actuall CTF.I made a pic and an error term.(which one is mask which one is colourmap is for you to crack)

[dardoro]

uses lossless PNG compression.
So any extra information you are trying to hide inside images is still there after loading.
The problem is caused by anti-aliasing. An image can be created by using data-URL or "stamped" onto canvas with drawImage(). Depending on scaling and imageSmoothingEnabled image may become "distorted" - extra pixels and color changes appear near the edges.
It's a matter of trials&errors to get the desired result with "proper" scale and costume size.
Sometime its a "one-shot" solution. Re-save can destroy the info.

I stored the info for CTF.1 in the dynamic costume for Stage and it's still there.

[d4s_over_dt4]

@dardoro

uses lossless PNG compression.

Yeah,I knew that snap used png,but thought that jpeg was the only lossless format

@dardoro

Depending on scaling and imageSmoothingEnabled image may become "distorted" - extra pixels and color changes appear near the edges.

Oh ok.

(do you want to try my ctf3?i fixed the aliasing by posting the content in the forum)

[bh]

@d4s_over_dt4

thought that jpeg was the only lossless format

It's not a lossless format. If you want lossless, use tiff. Isn't that right?

[ego-lay_atman-bay]

@d4s_over_dt4

thought that jpeg was the only lossless format

Jpeg is lossy, png is lossless

[d4s_over_dt4]

yeah i mixed them