1. Refactor Bitmap.cpp/h to expose the options for FloydSteinberg and
brightness/gamma correction at runtime
2. Fine-tune the thresholds for Floyd Steiberg and simple quantization
to better match the display's colors
Turns out that 2 is enough to make the images render properly, so the
brightness boost and gamma adjustment doesn't seem necessary currently
(at least for my test image).
Added a setting to select `fit` or `crop` for cover image on sleep
screen.
Might add a `expand` feature in the future that does not crop but rather
fills the blank space with a mirror of the image.
---------
Co-authored-by: Dave Allie <dave@daveallie.com>
## Summary
* Swap to updated SDCardManager which uses SdFat
* Add exFAT support
* Swap to using FsFile everywhere
* Use newly exposed `SdMan` macro to get to static instance of
SDCardManager
* Move a bunch of FsHelpers up to SDCardManager
## Summary
* **What is the goal of this PR?**
Replace simple threshold-based grayscale quantization with ordered
dithering using a 4x4 Bayer matrix. This eliminates color banding
artifacts and produces smoother gradients on e-ink display.
* **What changes are included?**
- Add 4x4 Bayer dithering matrix for 16-level threshold patterns
- Modify `grayscaleTo2Bit()` function to accept pixel coordinates and
apply position-based dithering
- Replace simple `grayscale >> 6` threshold with ordered dithering
algorithm that produces smoother gradients
## Additional Context
* Bayer matrix approach: The 4x4 Bayer matrix creates a repeating
pattern that distributes quantization error spatially, effectively
simulating 16 levels of gray using only 4 actual color levels (black,
dark gray, light gray, white).
* Cache invalidation: Existing cached `cover.bmp` files will need to be
deleted to see the improved rendering, as the converter only runs when
the cache is missing.
## Summary
* Handle 16x16 MCU blocks in JPEG decoding
* We were only correctly handling 8x8 blocks, which means that we did
not correctly support a lot of JPGs leading to an interlacing style on
the images
## Additional Context
* Fixes https://github.com/daveallie/crosspoint-reader/issues/118
## Summary
- Add basic JPG image support
- Map JPG back to 2-bit BMP output
- Can be used to later render the BMP file from disk or directly pass to
output if wanted
- Give the 3 passes over the data needed to render grayscale content,
putting it on disk is preferred to outputting it multiple times
## Additional Context
- WIP, looking forward to BMP support from
https://github.com/daveallie/crosspoint-reader/pull/16
- Addresses some of #11
