# image_utils

**Repository Path**: adoontheway/image_utils

## Basic Information

- **Project Name**: image_utils
- **Description**: dart 图片解析，压缩等其他一些工具
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2022-10-03
- **Last Updated**: 2022-10-13

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# ado_image

A flutter library intented to do some simple image process.

# Features 
- [ ] Distinct Image format by content, not file ext
   - [x] isPng 
   - [ ] isJpg 
- Uint8List Read
   - [x] read short(2 byte)
   - [x] int32 (4 bytes) from Uint8List 
- Image Reader 
   - [x] PNGReader
   - [ ] JpgReader
   - [ ] WebpReader
   - [ ] GifReader
   - [ ] Base64Reader
- [ ] Compress Algorithm
   - [ ] luban
   - [ ] others like quotation 
- [ ] Sprite Split 
- [ ] Image Resize 
- [ ] Image Format convert 
- [ ] Audio Format Convert
- [ ] Audio Compress 

# Reference for myself

## Specification of PNG
### five types of png
#### transformation of the reference image results i
* Truecolour with alpha: each pixel consists of four samples: red, green, blue, and alpha.
* Greyscale with alpha: each pixel consists of two samples: grey and alpha.
* Truecolour: each pixel consists of three samples: red, green, and blue. The alpha channel may be represented by a single pixel value. Matching pixels are fully transparent, and all others are fully opaque. If the alpha channel is not represented in this way, all pixels are fully opaque.
* Greyscale: each pixel consists of a single sample: grey. The alpha channel may be represented by a single pixel value as in the previous case. If the alpha channel is not represented in this way, all pixels are fully opaque.
* Indexed-colour: each pixel consists of an index into a palette (and into an associated table of alpha values, if present).
#### the pixel the samples appear 
* Truecolour with alpha: red, green, blue, alpha.
* Greyscale with alpha: grey, alpha.
* Truecolour: red, green, blue.
* Greyscale: grey.
* ghyr5tIndexed-colour: palette index.

### Chunk naming conventions
* [REC-PNG-20031110](https://www.w3.org/TR/2003/REC-PNG-20031110/#11zTXt)
>> cHNk  <-- 32 bit chunk type represented in text form
   ||||
   |||+- Safe-to-copy bit is 1 (lower case letter; bit 5 is 1)
   ||+-- Reserved bit is 0     (upper case letter; bit 5 is 0)
   |+--- Private bit is 0      (upper case letter; bit 5 is 0)
   +---- Ancillary bit is 1    (lower case letter; bit 5 is 1)


#### Critical Chunk
* IHDR
* PLTE
* IDAT
* IEND



## Reference
* [PNG Specification ](http://www.libpng.org/pub/png/spec/)
* [ PNG图像格式解析 ](https://blog.csdn.net/weixin_45715387/article/details/115181935)