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[攝影] what software U use to rotate the pic without resolution loss?! [複製鏈接]

DomanFans

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發表於 05-6-15 11:33 |只看該作者

what software U use to rotate the pic without resolution loss?!

As above.

When the digital photos are saved to computer, and I want to rotate it, I have tried using photoshop, irfanview, acdsee. But I find that the filesize after rotation become significantly changed (even if I set the compression ratio to 100%).

I understand that it is the compression algorithm of JPEG that everytime the file is saved, it do some compression with loss in quality.

Is there any software that U use to rotate the photos without (or with little) quality loss?

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夾心人

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發表於 05-6-15 20:56 |只看該作者

Re: what software U use to rotate the pic without resolution loss?!

任何有 jpegtran 功能的軟件皆可以做到，如 betterjpg, cPicture, jpegcrop ........

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kaikai88

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發表於 05-6-15 21:40 |只看該作者

Re: what software U use to rotate the pic without resolution loss?!

I opened a 2.64MB photo with Photoshop 7.0, saved it without making any modification with highest quality (12). The photo became 3.26MB.

It seems to indicate that the compression used by Photoshop for highest quality is even less than that used by the camera.

JPEG compression must be lossy. I think Photoshop is already producing very high quality result.

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kaikai88

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發表於 05-6-15 21:41 |只看該作者

Re: what software U use to rotate the pic without resolution loss?!

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DomanFans

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發表於 05-6-24 17:30 |只看該作者

Re: what software U use to rotate the pic without resolution loss?!

夾心人寫道:
任何有 jpegtran 功能的軟件皆可以做到，如 betterjpg, cPicture, jpegcrop ........

is there any lose of picture quality?

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夾心人

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發表於 05-6-24 22:13 |只看該作者

Re: what software U use to rotate the pic without resolution loss?!

沒有 lose of picture quality (我假設你的意思是改變了)。

你可以自己證實。

1) 為著可以比較，相片要與原相一樣方向才可，哪用有jpegtran功能的軟件將相先向右轉90度，save一次，再左轉90度，save一次。

2) 用PS開啟原文件，再開啟該轉了兩次的文件，將圖層複制去原相的文件作新圖層。

在原相的文件，將該新圖層設成差異化，你可以看到顯示是全黑的，這表示兩原相跟新的圖層是一樣的。但別信自己的眼，使用mouse在畫面移動，觀察資訊窗口的 RBG值全是 0 才是真的全黑。

3) 試用其它軟件，做兩次90度轉動及save。再用前一步驟 (#2)的做法，看看資訊的顯示，如果發現有任何地方不是 RGB 0,0,0 的代表相片在轉動的時候被改變了資料。

我曾用PS做轉動再與原相比較，RGB值有 0-4 %的不同。

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