8 ms·

Honestly, I don't consider PNG a simple format. The CRC and the compression are non-trivial. If you're using a new language that doesn't have those features bui

• SideQuark 4y ago
  > The CRC and the compression are non-trivial. CRC is a table and 5 lines of code. That's trivial. >zlib is 23k lines It's not needed to make a PNG reader/writer. zlib is massive overkill for only making a PNG reader or writer. Here's a tiny deflate/inflate code [2] under 1k lines (and could be much smaller if needed). stb[0] has single headers of ~7k lines total including all of the formats PNG, JPG, BMP,. PSD, GIF, HDR, and PIC. Here's [1] a 3k lines single file PNG version with tons if #ifdefs for all sorts of platforms. Removing those and I'd not be surprised if you could not do it in ~1k lines (which I'd consider quite simple compared to most of todays' media formats). >Of course they're not common formats so you're stuck with complex formats like PNG BMP is super common and easy to use anywhere. I use flat image files all the time for quick and dirty stuff. They quickly saturate disk speeds and networking speeds (say recording a few decent speed cameras), and I've found PNG compression to alleviate those saturate CPU speeds (some libs are super slow, some are vastly faster). I've many times made custom compression formats to balance these for high performance tools when neither things like BMPs or things like PNG would suffice. [0] https://github.com/nothings/stb https://github.com/nothings/stb [1] https://github.com/richgel999/fpng/blob/main/src/fpng.cpp https://github.com/richgel999/fpng/blob/main/src/fpng.cpp [2] https://github.com/jibsen/tinf/tree/master/src https://github.com/jibsen/tinf/tree/master/src
• IYasha 4y ago
  Um... for the record: BMP and TGA may have compression. And, since it is rarely implemented, you may crash a lot of stuff with your RLE bitmap )
• Galanwe 4y ago
  Agree. Programming video games in the early 2000s, TGA was my goto format. Dead simple to parse and upload to OpenGL, support for transparency, true colors, all boxes ticked.
  • Tepix 4y ago
    I had forgotten about that but yes, TGA was easy to deal with even doing low level programming.
  • actionfromafar 4y ago
    I always used PCX for some reason I can't remember.
    • AnIdiotOnTheNet 4y ago
      Possibly because it was also used by Andre LaMothe's original Tricks of the Game Programming Gurus book?
    • influx 4y ago
      I once wrote a PCX decoder in Pascal outputting VGA w/mode 13. The cool part for me was it had run length encoding, which I was able to figure out trivially just reading the spec. May not have been the most efficient, but way easier than trying to figure out GIF!
• ivoras 4y ago
  It depends mostly on the year of birth of the beholder. I imagine in a couple of decades that "built-in features" of a programming environment will include Bayesian inference, GPT-like frameworks and graph databases, just as now Python, Ruby, Go, etc. include zlib by default, and Python even includes SQLite by default.
  • bluGill 4y ago
    Some languages will. However there will also be a constant resurgence brand new of "simple" languages without all of that cruft that "you don't need" (read whoever came up with the language doesn't need).
• twic 4y ago
  PPM is the ultimate simple format, particularly the plain form: https://netpbm.sourceforge.net/doc/ppm.html https://netpbm.sourceforge.net/doc/ppm.html
  • shadowofneptune 4y ago
    There's also the X Bitmap format: https://en.wikipedia.org/wiki/X_BitMap https://en.wikipedia.org/wiki/X_BitMap GIMP outputs it, which means you can make much any image embeddable into a C source.
• sprash 4y ago
  Even simpler is farbfeld which supports 16bit per channel + alpha. The header is nothing more than a magic string and image dimensions.
• IvanK_net 4y ago
  I have implemented a Zlib / Deflate decompressor (RFC 1951) in 4000 characters of Javascript. It could be shorter, if I did not try to optimize. E.g. this C implementation of Deflate adds 2 kB to a binary file: https://github.com/jibsen/tinf https://github.com/jibsen/tinf
• jodrellblank 4y ago
  Simple formats are PPM / Netpbm; they’re ASCII text with an identifier line (“P1” for mono, “P2” for grayscale or “P3” for colour), a width and height in pixels (e.g. 320 200), then a stream of numbers for pixel values. Line breaks optional. Almost any language that can count and print can make them, your can write them from APL if you want As ASCII they can pass through email and UUNET and clipboards without BASE64 or equivalent. With flexible line breaks they can even be laid out so the monochrome ones look like the image they describe in a text editor. See the examples at https://en.wikipedia.org/wiki/Netpbm# https://en.wikipedia.org/wiki/Netpbm#
  • st_goliath 4y ago
    The Netbpm format is amazing if you quickly want to try something out and need to generate an image of some sorts. The P6 binary format is even simpler, you write the header followed by a raw pixel data blob, e.g.: fprintf(stdout, "P6\n%d %d\n255\n", WIDTH, HEIGHT); fwrite(image, 1, WIDTH * HEIGHT * 3, stdout); Yes, I know, this obviously misses error handling, etc... The snippet is from a simple Mandelbrot renderer I cobbled together for a school exam exercise many moons ago: https://gist.github.com/AgentD/86445daed5fb21def3699b8122ea2b65 https://gist.github.com/AgentD/86445daed5fb21def3699b8122ea2... The simplicity of the format nicely limits the image output to the last 2 lines here.
    • a_e_k 4y ago
      I use this all the time. I love that it's simple enough that I can type something like those two lines off the top of my head at this point. And as an alternative to that fwrite(), another common pattern that I use is: for (int y = 0; y < HEIGHT; ++y) for (int x = 0; x < WIDTH; ++x) { // ... compute r, g, and b one pixel at a time printf("%c%c%c", r, g, b); } I also find ImageMagick very convenient for working with the format when my program writes a PPM to stdout: ./myprog | convert - foo.png or: ./myprog | display -
  • greggman3 4y ago
    I don't consider ASCII simple because it needs to be parsed (more than a binary format). As sample example, a binary format could be as simple as struct Header { uint32 width; uint32 height; } struct Image { Header header; uint8* data; } Image* readIMG(const char* filename) { int fd = open(filename, ...) Image* image = new Image(); read(fd, &image->header, sizeof(image->header)); size_t size = image->header.width * image->header.height * 4; image->data = malloc(size); read(fd, image->data, size); close(fd); return image; } Yea I know, that's not a complete example, endian issues, error checking. Reading a PPM file is only simple if you already have something to read buffered strings and parse numbers etc... And it's slow and large, especially for todays files.
• Denatonium 4y ago
  For audio, my all-time favorite format to work with is raw PCM. One time, I had to split a bunch of WAV files at precise intervals. I first tried ffmpeg, but its seeking algorithm was nowhere near accurate enough. I finally wrote a bash script that did the splitting much more accurately. All I had to do to find the byte offset from a timestamp in an raw PCM audio file is multiply the timestamp (in seconds) by the sample rate (in Hz) by the bit depth (in bytes) by the number of channels. The offset was then rounded up to the nearest multiple of the bit depth (in bytes) times the number of channels (this avoids inversions of the stereo channels at cut points). Once I had the byte offset, I could use the head and tail commands to manipulate the audio streams to get perfectly cut audio files. I had to admire the simplicity of dealing with raw data.
  • smcleod 4y ago
    That sounded quite fun, thanks for sharing.
  • speed_spread 4y ago
    Smart file systems should offer a way to access raw datastreams and elements within more complex filetypes. e.g. one could call fopen("./my_sound.wav/pcm_data") and not have to bother with the header. This would blur the distinction between file and directory, requiring new semantics.
• detrites 4y ago
  Another relatively simple format, that is apparently additionally superior to PNG in terms of compression and speed, is the Quite OK Image format (QOI): https://qoiformat.org/ https://qoiformat.org/ (And OT, but interesting, regarding their acronyms: P -> Q N -> O G->->I ...so close!)
• Retr0id 4y ago
  It would be nice if the CRCs and compression were optional features, but perversely that would increase the overall complexity of the format. Having compression makes it more useful on the web, which is why we're still using it today (most browsers do support BMP, but nobody uses it) The fun thing about DEFLATE is that compression is actually optional, since it supports a non-compressed block type, and you can generate a valid stream as a one-liner* (with maybe a couple of extra lines to implement the adler32 checksum which is part of zlib) The CRCs are entirely dead weight today, but in general I'd say PNG was right in the sweet-spot of simplicity versus practical utility (and yes, you could do better with a clean-sheet design today, but convincing other people to use it would be a challenge). *Edit: OK, maybe more than a one-liner, but it's not that bad https://gist.github.com/DavidBuchanan314/7559825adcf96dcddf023f361542c5ff https://gist.github.com/DavidBuchanan314/7559825adcf96dcddf0... Edit 2: Actual zlib deflate oneliner, just for fun: deflate=lambda d:b"\x78\x01"+b"".join(bytes([(i+0x8000)>=len(d)])+len(d[i:i+0x8000]).to_bytes(2,"little")+(len(d[i:i+0x8000])^0xffff).to_bytes(2,"little")+d[i:i+0x8000]for i in range(0,len(d),0x8000))+(((sum(d)+1)%65521)|(((len(d)+sum((len(d)-i)*c for i,c in enumerate(d)))%65521)<<16)).to_bytes(4,"big")
  • meindnoch 4y ago
    >The CRCs are entirely dead weight today Why? The usual answer is that "checksumming should be part of the FS layer". My usual retort to such an assertion is that filesystem checksums won't save you when the data given to the FS layer is already corrupted, due to bit flips in the writer process's memory. I personally have encountered data loss due to faulty RAM (admittedly non-ECC, thanks to Intel) when copying large amounts of data from one machine to another. You need end-to-end integrity checks. Period.
    • Retr0id 4y ago
      I agree with the "usual" answer, or more generally, "the layer above". We shouldn't expect every file format to roll its own error detection. If you truly care about detecting bit-flips in a writer process's memory, that's a very niche use-case - and maybe you should wrap your files in PAR2 (or even just a .zip in store mode!). 99% of in-the-wild PNGs are checksummed or cryptographically signed at a layer above the file format (e.g. as part of a signed software package, or served over SSL). Edit: Furthermore, the PNG image data is already checksummed as part of zlib (with the slightly weaker adler32 checksum), so the second layer of checksumming is mostly redundant.
• ajsnigrutin 4y ago
  BMP is really great, the whole format is described on wikipedia with enough detail to code it yourself in literally 10 minutes, and the 'hardest' part of creating (or parsing) a bmp is counting the bytes to pad the data correctly, and remembering where [0,0] is :) https://en.wikipedia.org/wiki/BMP_file_format#Example_1 https://en.wikipedia.org/wiki/BMP_file_format#Example_1
  • ape4 4y ago
    But there are lots of BMP versions - wiki says "Many different versions of some of these structures can appear in the file, due to the long evolution of this file format."
    • Retr0id 4y ago
      Exactly. It is easy to write a BMP reader, but if you want to read any BMP file that you might find in the wild then you're going to have a fun time.
      • duskwuff 4y ago
        There's even some very niche extensions to BMP which allow it to be used as a container for PNG or JPEG data. https://learn.microsoft.com/en-us/windows/win32/gdi/jpeg-and-png-extensions-for-specific-bitmap-functions-and-structures https://learn.microsoft.com/en-us/windows/win32/gdi/jpeg-and...
• ChrisMarshallNY 4y ago
  > complex formats like PNG I have written TIFF readers. Hold my ginger ale.
  • LoganDark 4y ago
    PPM reader!
    • ChrisMarshallNY 4y ago
      What is PPM? I’m not familiar with the acronym.
      • deathanatos 4y ago
        It's a particular variant of the Netpbm image format: https://netpbm.sourceforge.net/doc/ppm.html https://netpbm.sourceforge.net/doc/ppm.html It's dead simple to emit. The P6 binary version is just a short header, followed by RGB pixel data, one byte per channel. If you don't have a PNG encoder handy and need a quick "I just need to dump this image to disk to view it" for debugging, PPM is a great format due to how trivial it is. But it doesn't fit a lot of use cases (e.g., files are huge, because no compression).
        • ChrisMarshallNY 4y ago
          Ah, got it. TIFF, on the other hand is a "highest common denominator, lowest common denominator, what the hell, let's just throw every denominator -including uncommon ones- in there" format. For example, you can have images with four (or more) color channels, of different bit lengths, and different gammas and image characteristics (I actually saw these, in early medical imaging). You can have multiple compression schemes, tile-based, or strip-based layout, etc. A lot of what informed early TIFF, was drum scanners and frame captures. Writing TIFF: Easy. Reading TIFF: Not so easy. We would usually "cop out," and restrict to just the image formats our stuff wrote.
          • 4y ago
• luismedel 4y ago
  Agree. My go-to graphics format in the days of MCGA was PCX. Very easy to decode even with a small assembler routine.
• MisterTea 4y ago
  If you think PNG is complex have a gander at webp. That plane crash is a single frame of vp8 video. Outside of a Rube Goldberg web browser the format is useless.
  • lewispollard 4y ago
    WebP is useful for lossless image storage for games/game engines, it takes roughly 80% of the time to load/decode vs the same image stored as a png, and is usually significantly (multiple megabytes) smaller for large textures. That stuff doesn't matter too much in a web browser, but in a game where you have potentially hundreds of these images being loaded and unloaded dynamically and every millisecond counts, it's worthwhile.
    • MisterTea 4y ago
      That's a limited use case that I would consider embedded. The game player isn't interacting with those files directly.
      • lewispollard 4y ago
        So?
    • flohofwoe 4y ago
      Erm, aren't both WebP and PNG rather useless for games? How do you convert those formats on the fly into one of the hardware-compressed texture formats consumed by the GPU (like BCx, ETC or ASTC)? If you're decoding PNG or WebP to one of the linear texture formats, you're wasting a ton of GPU memory and texture sampling bandwidth. (these are probably better alternatives: https://github.com/BinomialLLC/basis_universal https://github.com/BinomialLLC/basis_universal, or http://www.radgametools.com/oodletexture.htm http://www.radgametools.com/oodletexture.htm)
      • lewispollard 4y ago
        Hardware compressed texture formats introduce compression artifacts, which is fine for some art styles or PBR maps that don't need to be super accurate, but for some styles (such as pixel art or "clean" non-pixel styles, in both 2d and 3d) lossless compression is preferred, and yeah they're just decoded into bitmap data on the fly. Whether it wastes memory or not is subjective and dependent on use case. Yeah if you're pushing 4k PBR maps for terrain to the gpu using lossless formats for storage that's not smart, but you could argue that for many textures, using VRAM formats wastes disk/download space vs lossless (especially on mobile devices or webgl/wasm where space matters more). If disk space/download size isnt a concern then uncompressed vram formats can work for smaller textures. Though there is an initial decoding/upload cost to compressed lossless images, and they're not optimised well for streaming, at least with pixel art that's not a huge concern as textures tend to have small dimensions, though a spritesheet in a VRAM format can quickly baloon to ridiculous sizes for what is otherwise low resolution artwork. Of all the open formats that support lossless compression, are easy to link against, with wide platform support, webp is good, and smaller/faster than png for basically all images. Basis universal is a decent solution to the disk size problem of traditional VRAM formats, but it still isn't lossless (afaik?). Oodle is new to me, it looks good, appears to solve all of the above if the blurb is to be believed; it's a shame it's proprietary. I'd use it right away if it was FOSS.
• Cloudef 4y ago
  One of the annoyances of TGA format is that they have no signature at beginning of the file. The signature is at bottom. This allows you to craft a TGA file that could be misidentified.
• 082349872349872 4y ago
  > zlib is 23k lines. The zlib format includes uncompressed* chunks, and CRC is only non-trivial if you're also trying to do it quickly, so a faux-zlib can be much, much smaller. (I don't recall if I've done this with PNG specifically, but consider suitably crafted palettes for byte-per-pixel writing: quick-n-dirty image writers need not be much more complex than they would've been for netpbm) * exercise: why is this true of any reasonable compression scheme?
  • cylemons 4y ago
    The "compressed" file may end up larger than the original?
    • artiii 4y ago
      why not? most formats have some headers and some kind of frames with data (additional headers)
  • Dylan16807 4y ago
    > why is this true of any reasonable compression scheme? Any? I wouldn't say that. If you took LZ4 and made it even simpler by removing uncompressed chunks, you would only have half a percent of overhead on random data. A thousandth of a percent if you tweaked how it represents large numbers.
    • 082349872349872 4y ago
      TIL. IIUC, LZ4 doesn't care about the compression ratio (to which you are correct I had been alluding) but does strongly care about guaranteeing a block maximum size. (so still the same kind of concern, just on an absolute and not a relative basis)
      • Dylan16807 4y ago
        Just simplify it further. Get rid of the implicit +4 to the match size. 0-15 instead of 4-19. Now you can guarantee any block size you want. If you wanted to go even simpler, here's an entire compression format described in one line: one byte literal length, one byte match length, two bytes match offset, 0-255 literal bytes, repeat
• pornel 4y ago
  PNG is not a format for uncompressed or RLE "hello worlds". It's a format designed for the Web, so it has to have a decent compression level. Off-the-shelf DEFLATE implementations were easily available since its inception. I think it is pretty pragmatic and relatively simple, even though in hindsight some features were unnecessary. The CRC was originally a big feature, because back then filesystems didn't have checksums, people used unreliable disks, and FTPs with automatic DOS/Unix/Mac line ending conversions were mangling files. PNG could be simpler now if it didn't support 1/2/4-bit depths, keyed 1-bit alpha for opaque modes, or interlacing. But these features were needed to compete with GIF on low-memory machines and slow modems. Today, latest image formats also do this competition of ticking every checkbox to even worse degree by adding animation that is worse than any video format in the last 20 years, support all the obsolete analog video color spaces, redundant ICC color profiles alongside better built-in color spaces, etc. By modern standards PNG is super simple.
  • PaulHoule 4y ago
    There was talk about upgrading PNG to support the equivalent of animated GIFs but it never really happened because of complexity, see https://en.wikipedia.org/wiki/Multiple-image_Network_Graphics https://en.wikipedia.org/wiki/Multiple-image_Network_Graphic... As for color spaces that is a case where things get worse before they get better. In the 1990s I remember the horror of making images for the web with Photoshop because inevitably Photoshop would try some kind of color correction that would have been appropriate for print output but it ensured that the colors were wrong every time on the screen. Today I am seeing my high color gamut screen as a problem rather than a solution because I like making red-cyan anaglyph images and found out that Windows makes (16,176,16) when I asked for (0,180,0) because it wants to save my eyes from the laser pointer green of the monitor by desaturating it to something that looks like sRGB green to my eyes, but looking through 3d glasses it means the right channel blends into the left channel. To get the level of control I need for this application it turns out I need to make both sRGB and high gamut images and display the right one... Which is a product of the complexity of display technology and how it gets exposed to developers.
    • edflsafoiewq 4y ago
• netr0ute 4y ago
  > zlib is 23k lines I don't know, because zlib makes concessions for every imaginable platform, has special optimizations for them, plus is in C which isn't particularly logic-dense.
• dekerta 4y ago
  I really like QOI (The Quite OK Image format). It achieves similar compression to PNG, but it's ridiculously easy to implement (the entire spec fits on a single page), and its encoding and decoding times are many times faster than PNG. https://qoiformat.org https://qoiformat.org
  • Retr0id 4y ago
    It depends on the implementation. fpng can beat QOI in both speed and compression ratio https://github.com/richgel999/fpng https://github.com/richgel999/fpng
  • masklinn 4y ago
    > It achieves similar compression to PNG It really doesn’t, even on Wii’s own curated corpus qoi is often >30% larger, and on worst case scenarios it can reach 4x.
  • JD557 4y ago
    I'm also a big fan of QOI as a simple imagine format. Yes, it's not as good as PNG (as the sibling comments point out), but I view it more as an alternative to PPM (and maybe a BMP subset), as something that I can semi-quickly write an encoder/decoder if needed. IMO, PNG is in a completely different level. Case in point, in the linked article the author mentions to not worry about the CRC implementation and "just use a lib"... If that's the case, why not just use a PNG lib?
• giantrobot 4y ago
  While PNG is definitely not as simple as TGA, I'd say it's "simple" in that it's spec is mostly unambiguous and implementing it is straight forward. For its relative simplicity it's very capable and works in a variety of situations. One nice aspect of PNG is it gives a reader a bunch of data to validate the file before it even starts decoding image data. For instance a decoder can check for the magic bytes, the IHDR, and then the IEND chunk and reasonably guess the file is trying to be a PNG. The chunks also give you some metadata about the chunk to validate those before you even start decoding. There's a lot of chances to bail early on a corrupt file and avoid decode errors or exploits. A format like TGA with a simplistic header and a blob of bytes is hard to try validating before you start decoding. A file extension or a MIME header don't tell you what the bytes actually are, only what some external system thinks they are.