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photowiki:post [2016/11/17 04:26]
ying [RAW vs 16-bit tiff]
photowiki:post [2017/02/04 19:41] (current)
ying [HDR Merge]
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 ===== RAW vs 16-bit tiff ===== ===== RAW vs 16-bit tiff =====
 +
 +  * watch this video first: http://​tv.adobe.com/​watch/​the-complete-picture-with-julieanne-kost/​the-advantages-of-the-dng-file-format/​
 +  * http://​photo.net/​learn/​raw/​
 +
  
   * ref: http://​forum.luminous-landscape.com/​index.php?​topic=57894.msg467946#​msg467946   * ref: http://​forum.luminous-landscape.com/​index.php?​topic=57894.msg467946#​msg467946
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   * Whenever there is a gradient in the background in your image, make sure you are working in 16-bit color depth to avoid banding of colors.   * Whenever there is a gradient in the background in your image, make sure you are working in 16-bit color depth to avoid banding of colors.
 +
 +====== Words about digital photo editing and creation ======
 +
 +  * if you can't get a wide-angle lens like 11mm, \\ you can always stitch a 180 degree panorama with several side-by-side shots taken with normal-angle lens like 28mm
 +  * if you can't get a 18MegaPixel camera \\ you can always put a grid shots of 3MegaPixel photos together.
 +  * if you can't get a dynamic range from your sensor, \\ you can always shoot mutiple shots with different exposure and stitch together.
 +  * if you can't get a large aperture lens to create a background-blurry portrait shot, \\ you can always blur the background manually in photo editing softwares.
 +
 +Because
 +  - Wide angles lens are expensive
 +  - large aperture lens are expensive
 +  - MegaPixel sensor camera used to be expensive (my 1st camera is 3MP)
 +  - High sensitivity sensor camera are expensive
 +
 +We achieve the same thing digitally with free photo eiditing software, [[https://​krita.org/​en/​|Krita]] or [[http://​www.gimp.org/​|GIMP]].
 +
 +====== Digital Only stuff ======
 +
 +  * Moire pattern effect and AA (anti-alias) process and Low Pass filter
 +    * http://​www.wfu.edu/​~matthews/​misc/​DigPhotog/​alias/​
 +    * http://​mansurovs.com/​what-is-low-pass-filter
 +
 +====== HDR Merge ======
 +
 +  * Tone mapping tips: http://​www.lightstalking.com/​5-important-tone-mapping-tips
 +
 +  * Exposure Value and Exposure stops: http://​www.reedbeta.com/​blog/​2014/​06/​04/​artist-friendly-hdr-with-exposure-values/​
 +  * pixel brightness and exposure stops: http://​www.scratchapixel.com/​lessons/​3d-advanced-lessons/​things-to-know-about-the-cg-lighting-pipeline/​0-18-stop-and-exposure-explained/​
 +
 +====== Color Grading ======
 +
 +  * video tut: cn TangWan: http://​www.chinahunpai.com/​play1435.html
 +
 +
 +  * style 1 (white/​cyan/​contrast):​ ([[http://​sosli.poco.cn|ref]])
 +    * cleanup and sharpen
 +    * lighten the face before clipping (drag highlight in level)
 +    * cyan the shadow
 +    * skin soften by soft light blend of BW filter (high contrast red filter)
 +    * saturate facial color
 +
 +  * style 2 (yellow/​cyan/​low contrat) ([[http://​www.swcool.com/​html/​article/​sanwen/​333.html|ref]])
 +    * skin: (red/​yellow) - cyan - magenta - yellow - black  + saturate + light
 +    * shadow: (blue/​black) -cyan + magenta + yellow + black
 +    * neutral: + yellow
 +    * 2nd pass color tuning
 +    * lower highlight curve to reduce contrast
 +    * lighten highlight in level to brighten, middle point to balance color
 +    * channel mix to boost color channel a bit more
 +    * color contrast: white/​yellow - cyan - yellow - black; ​
 +
 +====== Common Technique ======
 +
 +  * Green Leaf to Orange Yellow Leaf
 +    * yellow (Abs -70% cyan=+70% red (affect light green part), -50% yellow (-saturation))
 +    * green (Abs -75% cyan (affect deep green part), +10% meganta (+aging+saturation),​ +50% yellow (+saturation))
 +    * black (Abs, -cyan (dark->​red),​ -meganta(dark->​green))
 +    * color balance: shadow+mid (+megenta); hightlight (+yellow)
 +
 +  * soft light look
 +    * 40% color-filled top layer in screen mode
 +
 +  * color replacement
 +    * paint layer with hue mode
 +
 +  * color style
 +    * white light cyan: pure, light, clean
 +    * orange warm: energy, warm, home
 +    * cyan white cold: modern, stylish, fashion
 +
 +  * control of Hightlight, Middle Tone, Shadow Area
 +    * selection method:
 +      * load from RGB channel (as white is more selected, dark is not selected)
 +      * color range (white, grey, black)
 +      * calculation (math way for selection making)
 +        * hightlight: grey in screen;
 +        * shadow: inverted grey in screen;
 +        * middle tone: grey in exlusion
 +
 +  * steps of a color-grading approach
 +    - decide your color style
 +    - make a duplicate layer - environment ​
 +      - apply Selective Color and Color Balance and Curve to get the rough color and exposure ​
 +    - make a duplicate layer - shadow
 +      - apply Selective Color to tune the shadow to the look
 +      - get Shadow Masking to that layer
 +    - make a duplicate layer - highlight
 +      - apply Selective Color to tune the shadow to the look
 +      - get Highlight Masking to that layer
 +    - make a duplicate layer - skin
 +      - apply selective color to tune the skin to the look
 +      - paint masking to show the skin area.
 +    - apply final grading and color tunes
 +    - if any parts need to be specifically tuned, duplicate and tune it seperately
 +====== Skin Perfection======
 +
 +  * skin perfection introduction:​ [[http://​jingyan.baidu.com/​album/​f3ad7d0fc77a2d09c3345b34.html|link]]
 +    * method - [[http://​jingyan.baidu.com/​album/​77b8dc7f2707456174eab6c0.html|channel curve mask]]
 +
 +Of course, before any below method, please use heal brush or patch tool to fix big holes of skins
 +
 +**Overlay + Invert + Highpass Filter (blur) + Gaussian Blur Filter (sharp) Method**
 +  - duplicate layer and apply overlay blend mode
 +  - invert layer
 +  - add highpass filter to blur it like 10 point setting
 +  - then Gaussian blur filter to sharp it a bit
 +  - mask
 +
 +**Highpass filter (3x,18), Gaussian Blur (1x, 6), Invert, Linear Light mode (corner blend option)**
 +  - duplicate layer
 +  - highpass filter (3x, 18)
 +  - Gaussian blur filter (1x, 6)
 +  - Invert
 +  - linear light mode (corner blend option)
 +  - mask
 +
 +**Median Filter (10) **
 +  - duplicate layer
 +  - Noise: Median Filter (10)
 +  - mask
 +
 +**Surface Blur Filter (5,15)**
 +  - duplicate layer
 +  - Blur: Surface Blur Filter (5,15)
 +  - mask
 +
 +**Highpass Filter (10), De-saturate,​ Invert, Softlight/​Hardlight mode **
 +  - duplicate layer
 +  - highpass filter (10) to get details,
 +  - de-saturate to get detail line information only
 +  - Invert to get smooth area information only
 +  - softlight/​hardlight mode to blend into smooth area
 +  - mask
 +
 +Summary of all above method and theories behind it:
 +  * ref: https://​fstoppers.com/​post-production/​ultimate-guide-frequency-separation-technique-8699
 +
 +**and more scientific accurate way of detail (high frequency image data) and smooth area (low frequency image data)seperation and process**
 +
 +  - prepare layers:
 +    - high frequency layer: fill with 50% gray
 +    - low frequency layer: duplicated image with Gaussian Blur all fine detail.
 +  - write out into high frequency layer
 +    - select high frequency layer, choose Apply Image (8 bit, Source: LowFrequencyLayer,​ RGB, Subtract, scale 2, offset 128) 
 +    - linear light mode
 +  - soften and even out color and tone transitions on the Low Frequency layer
 +
 +===== Oil Spot removal =====
 +
 +  * clone tool
 +    * **steps**:
 +      - use 30%~50% clone the edge around it to surround it slowly to eat it out, 
 +      - but the things are, when tons of little oil spots, there is no clean area to clone with
 +      - force the brush will cause bad brightness change overall, then you need to lower the opacity and flow of brush to ease the blends of clone
 +  * heal brush
 +    * **step**
 +      - use small brush and heal the dots out,
 +      - best of heal is auto blend the brightness of the spot, but sometimes it left with a patch outline
 +
 +
 +====== Use before Shots ======
 +
 +  * water bottle spread mirror for low angle sun shot
 +
 +
 +====== additional ref ======
 +
 +  * coloring: http://​www.3lian.com/​edu/​photoshop/​pstiaose/​