[wilwilson2003]

how big is the quality different raw and jpg?

[wilwilson2003]

is the mb of it alot bigger than jpg ???how big as ?

[sevensister]

RAW 只是由感光元件 capture 出的原始數據
本身未經後製軟件 convert 出的話並不可讀
不能作為比較, 就像底片一樣

理論上如果 convert 軟件 跟 digicam 的設定一樣的話
所轉出的 JPG 檔質素應該是一樣的

那麼為什麼要保留 RAW ?
有幾個重要原因
1.)
RAW 的 sampling 為 12-bit /10-bit ,
要保留全部資訊的話可以 convert 為 16-bit 的 TIFF
而 JPG 每 channel 只有 8-bit.
2.)
JPG 本身為破壞性的壓縮, 每次轉存都會令畫質再一次下降, 不利後製
3.)
RAW data convent 之前有很多的調整空間, 這些調整都是 JPG 做不到的
eg.
a. 色溫可以任意調較
b. 曝光 over / under 2級都可以補償
c. 可以改善原廠相機內過柔/過硬的設定
d. 出色的 convert 軟件轉出的 raw 畫質更細緻, noise 更少
這些特性非常像傳統攝影的底片
所以 RAW 愈來愈受攝影人重視, 從各家大廠都提供 RAW 可見一班

RAW 檔有多大要視乎它的是 12bit 還是 10-bit 的 sampling 及有否壓縮而定
例如 olympus 的 5MP 10-BIT RAW (ORF) 就有 10MB
Canon 6MP 的 Compressed RAW (CRW) 就只有 6MB
5MP 的 JPG (SHQ 1:2.7)) 大約 3.8MB

小弟淺見, 如有錯漏請不吝指正, 非常感謝

[cell]

多謝提供。

因為我都想用RAW睇睇執相校果如何。

[ricer]

我真的不懂，只知是最原始檔，CCD讀到什麼，Raw就是什麼。儲存了Raw，我要如何「後期製作」也可以，十年後不喜歡當時的口味嗎？拿Raw出來再調整過。Jpeg就不能再undo了。

而且，Raw可以轉jpeg儲存，jpeg就不能還原回 Raw，所以我寧願以Raw mode拍攝。況且論file size, 即些零壓縮的ultra fine mode絕不比raw細。

個人意見，希望大家也作分享，讓我學習學習。

[ninekit]

a little tip, if you really intended to use RAW as your ultimate archive format. pls. make sure you zip your RAW reader/converter and safely get them archived as well. Or better, your whole PC / OS, the particular version of photoshop or what ever imaging software your RAW developer used as a plug-in and etc.

i am primarily a fan of RAW as well, but as a matter of fact, some professionals who is pioneers to use some earlier Pro DLSR made by Kodak/Canon found it a pain to re-use their RAW file archives, just because their camera is no longer supported, and Photoshop move from version 5 to 7 , Mac OS also moved a couple generations, not even need to mention MS windows la.

who knows whether our beloved camera manufacturer will still be in the market or not. so for safety, and future proof, its better to archive both the RAW file, the RAW developer as well as a pre-colour corrected/sharpened large JPEG of your picture. Then, the chance for you can re-use your picture in 10 yrs time will be higher.

for similiar reason, becuase of my old SCSI film scanner, i am still using Windows 98se.

[ricer]

Never mind, save a copy of tiff file as backup.