No Tiff support.

[JimBobSquarePants]

From @JimBobSquarePants on August 31, 2016 1:49

We should be able to support TIFF

Useful links.

http://partners.adobe.com/public/developer/tiff/index.html

http://www.remotesensing.org/libtiff/

http://www.awaresystems.be/imaging/tiff.html

Current implementation can be found in the tiff-codec branch.

Feature Checklist

• Reading TIFF file structure
• Parsing of relevant metadata
• Extraction of image data blocks
• Construction of image (from strip data)
• Construction of image (from tile data)

Compression Types

• None
• Ccitt1D
• PackBits
• CcittGroup3Fax
• CcittGroup4Fax
• Lzw
• Old Jpeg
• Jpeg (Technote 2)
• Deflate (Technote 2)
• Old Deflate (Technote 2)

Photometric Interpretation Formats

• WhiteIsZero
• BlackIsZero
• Rgb (Chunky)
• Rgb (Planar)
• PaletteColor
• TransparencyMask
• Separated (TIFF Extension color spaces)
• YCbCr (TIFF Extension color spaces)
• CieLab (TIFF Extension color spaces)
• IccLab (TechNote 1)

[JimBobSquarePants]

From @kierenj on September 7, 2016 20:27

I realise how unhelpful this comment right here is, but TIFF decoding across the board can be really tricky to get right - there are loads of compression formats, and even fairly respected tools (from MS / Atalasoft) get it wrong even with 1-bit images. I think some archiving formats even require special licensing to implement correctly. It might be worth identifying a small subset of formats to support!

[JimBobSquarePants]

@kierenj It's certainly not an unhelpful comment. Tiff would be hard and I'm sorely tempted to let someone else figure it out and concentrate on what we have already. I'm just dreading the day someone tells me that the library is useless without it. There's always someone!

[ChrisVanDijk]

I needed to import Tiff files so I created a temporary Tiff encoder and decoder based on LibTiff.Net.

[JimBobSquarePants]

@ChrisVanDijk Good effort but have you benchmarked that codec? The Bitmiracle jpeg codec was about 10x slower and used 190MB more to process a small test image compared to our codec. I imagine the Tiff one will be the same. I'd be careful using it.

@Andy-Wilkinson you have been playing around with Tiff haven't you with your own stuff? I wonder if we can use some of it?

[ChrisVanDijk]

@JimBobSquarePants The code and performance is bad, but I really needed the ability to open Tiff files. It's a temporary solution until a better one.

[JimBobSquarePants]

@ChrisVanDijk understandable. Tiff is a complex format so I'm pushing it to the backburner until I can get everything else out of the way... Not looking forward to tackling it!

[antonfirsov]

@ChrisVanDijk @JimBobSquarePants One big "advantage" of these naive C ports is that its really not that hard to make the first steps towards speeding & cleaning them up.
Someone with time & a profiler could check it, and estimate the efforts needed reuse/refactor elements of that code.

[Andy-Wilkinson]

@JimBobSquarePants I've got the basics of reading the Tiff format itself working from my own project (I started here since many Camera Raw files are mutant Tiff files). As you mention, there are a number of compression formats, but the key ones probably aren't too much trouble. The one issue with my existing codebase is that it was a bit of an experiment in a more functional style of C#, rather than how you might structure it normally.

All that said, I know a fair amount about the Tiff format now, so probably would be able to make a quick start on a true ImageSharp Tiff codec pretty easily (and share a bit of the code where I can). Would you be interested in me picking up this issue and giving it a start? (especially since you guys seem to be busy enough with the existing codec perf 😄)

[JimBobSquarePants]

@antonfirsov I've found with those ports though there's about a million lines more code than I'd like to read nested in there.

@Andy-Wilkinson That would be absolutely brilliant if you could! 💯