一周多前在網(wǎng)上搜到的一篇技術(shù)文檔，覺得還不錯(cuò)。雖然平時(shí)用ps時(shí)大概也能知道哪種保存方式更合適，但基本停留在經(jīng)驗(yàn)基礎(chǔ)上，而這篇文章對(duì)另存為和另存為網(wǎng)頁(yè)格式有詳細(xì)的文件數(shù)據(jù)分析，覺得比較有做參考資料的價(jià)值，所以決定翻譯一下。翻譯之前覺得很短一篇，不過真正翻時(shí)感覺長(zhǎng)了五倍都不止，一看全篇英文就犯困，翻翻停停拖了很久才算差不多了。我用英文版ps，很多術(shù)語不清楚中文怎么說，外加英語爛，所以可能翻譯有些問題，望大家指正。--tea00

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原作者 www.impulseadventure.com
Photoshop Save As vs Save For Web
One of the more confusing options in Photoshop CS2 arises when it comes time to save your edited image. There are two methods to save your photo: using the Save As dialog box or using the Save For Web dialog box. This article answers the question: what are the differences between save for web and save as, and when should I use Save for Web?
Photoshop offers two options to save your image after editing:
• File -> Save As ...
• File -> Save For Web ...
Both of these menu otpions create an output JPEG file from your working image, but they differ in both the available options, flexibility and representation of JPEG compression quality.

Photoshop另存為和另存為網(wǎng)頁(yè)格式
Photoshop cs2中最易混淆的選項(xiàng)之一是在保存編輯過的圖片時(shí)，有兩種保存圖片的方式——另存和另存為網(wǎng)頁(yè)格式。本篇文章將解答另存和另存為網(wǎng)頁(yè)格式有何區(qū)別，以及何時(shí)應(yīng)該選擇保存為web格式。
Photoshop提供了兩種保存編輯過的圖片的方式
• 文件->另存為
• 文件->另存為網(wǎng)頁(yè)格式
兩種保存方式都可以輸出jpeg格式圖片，但兩種方式在jpeg壓縮質(zhì)量的選項(xiàng)、靈活度和表現(xiàn)上有所區(qū)別。

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Quick Choice
If you plan to...【You should use】
Create images for your website, or optimize the file as small as possible【Save For Web 】
Share images with others, and you want viewers knowing shot time/date, etc. 【Save As 】
Share images with others, and you do not want others knowing shot time/date, etc. For example, stock photos, or concerns over privacy 【Save For Web】
Convert your image to a given file size, or you want interactive feedback on quality settings 【Save For Web】
... for all other cases【Save As】

快速選擇
如果你想要…【那么選擇的保存方式是】
創(chuàng)建網(wǎng)頁(yè)使用的圖像，或者想盡可能的優(yōu)化圖像文件的體積【另存為網(wǎng)頁(yè)格式】
和他人分享圖片，而且你希望別人知道你拍攝照片的時(shí)間日期等【另存為】
和他人分享圖片，但你不希望別人知道你拍攝照片的時(shí)間日期等，比如用于圖片庫(kù)，或是需要保護(hù)隱私【另存為網(wǎng)頁(yè)格式】
把圖像文件壓縮到指定的大小，或者你想要在設(shè)定圖像質(zhì)量時(shí)能有交互的反饋【另存為網(wǎng)頁(yè)格式】
其它情況【另存為】

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Photoshop Save As
The Save As dialog includes a very large number of output file formats, as it is the standard method by which users will generate their final image files. As this output method is not optimized towards transmission over a low data-rate medium (such as the internet), additional information is encoded into the resulting image at the cost of increased file size. As shown below, this additional data may consume approximately 40KB.
One of the main reason that photographers choose Save As instead of Save for Web when sharing photos is so that the EXIF metadata (which includes camera information and shot details) can be displayed to other interested viewers. Most photo sharing sites (such as pbase) automatically extract this EXIF information, for the benefit of other photographers. However, considering that it also includes the time and date of the original shot, it may have privacy implications.

Photoshop 另存為
另存為是用戶輸出最終圖像文件的標(biāo)準(zhǔn)方式，因此對(duì)話框中有輸出多種文件格式的選擇。這種保存方式?jīng)]有為低速數(shù)據(jù)傳輸方式（例如互聯(lián)網(wǎng)）優(yōu)化文件，保存的圖像文件中包含了附加信息，因此文件體積較大。如后面所示，這些附加數(shù)據(jù)的體積可能接近40kb。
攝影者通常選擇另存為而不是另存為網(wǎng)頁(yè)格式的一個(gè)主要的原因是，在分享照片時(shí)，觀看者能夠查看到圖片的Exif信息（包括相機(jī)和拍攝信息）。大部分照片分享網(wǎng)站（例如pbase）都能自動(dòng)提取Exif信息，以方便其它攝影者查看。盡管如此，Exif信息包含著照片拍攝的時(shí)間日期信息，所以可能涉及隱私。

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16-bit Mode
As Save As does not support for 16-bit images, it may be necessary to convert to 8-bit first, save and then undo the color depth conversion step if you plan to continue working on the file. You can convert to 8 bit RGB by selecting Image -> Mode -> 8-bits/channel. Save for Web automatically converts the color depth for you.
16位模式
由于”另存為”不支持保存16位模式的圖像，所以有必要先轉(zhuǎn)換成8位模式，保存。如果你要繼續(xù)處理圖片的話，就撤銷上一步顏色位深的設(shè)置。把圖像轉(zhuǎn)為8位RGB圖像的方式是菜單上的圖像->模式->8位/通道。另存為網(wǎng)頁(yè)格式會(huì)自動(dòng)為你轉(zhuǎn)換顏色位深。

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Photoshop Save For Web
The Save For Web dialog box doesn't provide as much flexibility in the ouput image file formats as the Save As dialog, but it does offer more flexibility with each supported option. Supported output file formats include:
• JPEG - Selection of Quality level (1-100). No transparency.
• GIF - Different palette sizes (2-256) and dithering options define quality. Supports single-bit transparency.
• PNG-8 - Reduced color depth (2-256 colors) and dithering options defines quality. Supports multi-bit transparency.
• PNG-24 - "Lossless" 24-bit quality. Supports multi-bit transparency.
• WBMP - Black & White dithered output.
（附圖見下面的中文版）
Main window for Save for Web
The focus on this page will be on the JPEG output format.

Photoshop另存為網(wǎng)頁(yè)格式
另存為網(wǎng)頁(yè)格式?jīng)]有像另存為那樣提供很多中保存圖像文件的格式選擇，但是它為每種支持的格式提供了更靈活的設(shè)置。支持的格式包括：
• Jpeg－可以設(shè)置圖像保存質(zhì)量（1－100％）。無透明度。
• Gif－通過設(shè)置調(diào)色盤大?。?－256色）和顏色抖動(dòng)來確定保存圖片的質(zhì)量。支持單色透明度。
• Png-8－通過設(shè)置調(diào)色盤大小（2－256色）和顏色抖動(dòng)來確定保存圖片的質(zhì)量。支持單色透明度。（原文中png-8透明度的說法貌似有誤？）
• Png－24－無損24位質(zhì)量。支持透明度。
• Wbmp－黑白抖動(dòng)輸出。

另存為網(wǎng)頁(yè)格式的主窗口
按上圖中的設(shè)置將輸出jpeg格式文件。

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Save For Web JPEG output
Because the Save for Web command is intended to be used for images that are destined for display on the internet, one of the primary goals is in optimizing the file size as much as possible while still retaining acceptable image quality. To this end, two methods are used to achieve this: a) a live preview of changing JPEG compression quality sliders and b) the removal of all unnecessary metadata (JPEG markers) in the output file.
The main features in Save for Web include:
• Optimize to File Size: Ability to automatically select both the file format (JPEG or GIF) and JPEG compression level to achieve the selected file size.
• Removal of EXIF metadata. For many this is a useful feature, while others will completely avoid Save for Web because of it. For simple images on a web site or for privacy reasons, you may want to hide the time/date a photo was taken, or other parameters. But, if you plan to share your images on a photo hosting site and would like to indicate the focal length, aperture and other parameters to your viewers, Save for Web will not be the right method.
• Removal of Optional Markers. In most output JPEG files, special markers are used to indicate additional information or provide resiliency in the case of errors / corruption. The Save for Web method will remove these and still allow JPEG decoders to work.

另存為網(wǎng)頁(yè)格式之jpeg輸出
保存為網(wǎng)頁(yè)格式目的是輸出展示在網(wǎng)頁(yè)上的圖片，保存的主要的目的之一是在維持圖片質(zhì)量的同時(shí)盡可能地縮小文件體積。保存為網(wǎng)頁(yè)格式使用了兩種方法達(dá)到此目的：a) 在拖動(dòng)滑動(dòng)條更改jpeg質(zhì)量設(shè)置時(shí)提供即時(shí)預(yù)覽；b）移除輸出文件中所有不必要的信息（jpeg標(biāo)記）。
另存為網(wǎng)頁(yè)格式的主要特色有：
• 優(yōu)化文件大?。嚎梢宰詣?dòng)選擇文件格式（jpeg或gif）和選擇jpeg的壓縮率，以實(shí)現(xiàn)選定的文件大小。
• 移除Exif信息。很多時(shí)候這是一個(gè)有用的功能，而另一些人則會(huì)因?yàn)榇斯δ芏皇褂昧泶鏋榫W(wǎng)頁(yè)格式。對(duì)于簡(jiǎn)單的網(wǎng)頁(yè)圖片來說，或者出于保護(hù)隱私，你也許希望隱藏照片拍攝的時(shí)間日期以及其它參數(shù)。但是，如果你想要在網(wǎng)絡(luò)相冊(cè)中分享你的照片，并且希望觀看者看到拍攝的焦距、光圈和其它參數(shù)，那么就不適合使用另存為網(wǎng)頁(yè)格式了。
• 移除可選的標(biāo)記。在大多數(shù)jpeg文件中，有一些記錄附加信息、或是在出錯(cuò)/崩潰時(shí)用以恢復(fù)的特殊標(biāo)記。另存為網(wǎng)頁(yè)格式會(huì)在jpeg文件依然能被解碼的前提下移除這些標(biāo)記。

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ICC Color Profiles
Both Save for Web and Save As give you the option of including the ICC Color Profile within the image. Color profiles are used to the viewer's display how the RGB values within the image data should map to real-world colors. Assuming you have a color-managed environment (calibrated and profiled monitor), this profile is used to display the colors as they were intended to be shown.
Unfortunately, most web browsers don't read this profile and most people don't have calibrated monitors, so the default color space, sRGB is generally assumed. Therefore, if you are sharing your photos on the web, and your photos were shot in a color space such as Adobe RGB, it is strongly advised that you convert to sRGB first. Once you've done that, there is little need to include the ICC profile within the file.
Comparison of JPEG Markers
The differences between the output of the two JPEG compressed file saving methods is easily visible when comparing the JPEG (JFIF) files themselves. The JPEG (JFIF) file format specifies a number of mandatory markers as well as some optional ones. The chart below shows how Photoshop CS2 Save as and Photoshop CS2 Save for the Web compare at a low level, with the help of JPEGsnoop:

ICC顏色配置：
另存為網(wǎng)頁(yè)格式和另存為都提供了是否嵌入ICC顏色配置的選項(xiàng)。顏色配置是用來讓圖片文件的RGB數(shù)值在用戶顯示器上顯示出更真實(shí)的色彩。假設(shè)你有一個(gè)經(jīng)過顏色管理的環(huán)境（校準(zhǔn)和配置過的顯示器）配置能讓顏色顯示更接近預(yù)期的效果。
很不幸的是，大部分瀏覽器不支持顏色配置，并且大部分人沒有校準(zhǔn)過的顯示器，所以默認(rèn)假設(shè)是sRGB色彩空間。因此，如果你在網(wǎng)上分享照片，如果你的照片拍攝時(shí)使用的是其它色彩空間，例如Adobe RGB，那么強(qiáng)烈建議你轉(zhuǎn)換為sRGB。如果你這樣做的話，就基本不需要在文件中嵌入ICC顏色配置了。
通過對(duì)比jpeg文件，兩種jpeg壓縮文件保存方式的區(qū)別是很容易識(shí)別的。jpeg（jfif）文件格式中列入了一些強(qiáng)制的標(biāo)記和一些可選的標(biāo)記。下面的表格是photoshop另存為和另存為網(wǎng)頁(yè)格式的輸出文件的對(duì)比。

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Comparison of JPEG Markers in Photoshop
Save As　Save For Web　Description
SOI　　　SOI　　　　Start of Image marker
APP0　　APP0　　　　Identifier, Version, resolution, JFIF extensions
APP1　　　　　　　　EXIF data, Makernotes removed in both. (長(zhǎng)度 5KB)
APP13　　　　　　　　Photoshop IRB (Photoshop-specific data, including quality)
　　　　　　　　　　(長(zhǎng)度5KB)
APP1　　　　　　　　XML metadata (EXIF, IPTC, etc.) (長(zhǎng)度17KB)
APP2*　　APP2*　　　ICC color profile (* optional) (長(zhǎng)度3KB)
　　　　　APP12　　　Ducky tag - Save for Web Quality - stores the quality level
　　　　　　　　　　 (length 17B)
APP14　　APP14　　　Encoding info: color transform (e.g. YCbCr, YCCK, RGB, CMYK)
　　　　　　　　　　　and whether or not the samples were blended (length 14B)
DQT　　　DQT　　　　Quantization Tables
SOF0　　　SOF0　　　Baseline DCT, chroma subsampling
DRI　　　　　　　　　Restart Intervals - Adds a level of recovery in case of errors
　　　　　　　　　　　(length is variable, depends on frequency)
DHT　　　DHT　　　　Huffman compression tables
SOS　　　SOS　　　　Start of Scan: Image Data stream
EOI　　　　EOI　　　　End of Image marker
As can be seen in the above table, the additional data stored within a Save As JPEG versus as Save for Web JPEG is typically in the order of ~ 40 KB. In most high-resolution photos, this extra is insignificant, but when trying to compress small images for web use, this overhead could be significant.

Photoshop兩種保存方式輸出文件的jpeg標(biāo)記對(duì)比
另存為　另存為網(wǎng)頁(yè)格式　說明
SOI　　　SOI　　　　　圖像開始標(biāo)記
APP0　　APP0　　　　 識(shí)別標(biāo)記、版本、分辨率、jfif擴(kuò)展
APP1　　　　　　　　　EXIF數(shù)據(jù), 兩種保存方式都移除了制作者注釋(長(zhǎng)度5KB)
APP13　　　　　　　　　Photoshop IRB (Photoshop特有數(shù)據(jù),包括質(zhì)量) (長(zhǎng)度5KB)
APP1　　　　　　　　　XML數(shù)據(jù)(EXIF, IPTC等) (長(zhǎng)度17KB)
APP2*　　APP2*　　　　ICC顏色配置(*可選) (長(zhǎng)度3KB)
　　　　　APP12　　　　Ducky標(biāo)簽-保存為網(wǎng)絡(luò)格式質(zhì)量-儲(chǔ)存質(zhì)量等級(jí)(長(zhǎng)度17B)
APP14　　APP14　　　　編碼信息: 顏色轉(zhuǎn)換 (例如YCbCr, YCCK, RGB, CMYK)
　　　　　　　　　　　　以及樣本是否混合(長(zhǎng)度14B)
DQT　　　DQT　　　　　量化表
SOF0　　　SOF0　　　　基線DCT, 色度抽樣
DRI　　　　　　　　　　重新開始間隔-加入出錯(cuò)時(shí)的復(fù)原標(biāo)準(zhǔn)(長(zhǎng)度不定)
DHT　　　DHT　　　　　Huffman壓縮表
SOS　　　SOS　　　　　掃描開始: 圖像數(shù)據(jù)流
EOI　　　EOI　　　　　圖像結(jié)束標(biāo)記
如上表所示，另存為輸出文件所包含的附加信息使文件比另存為網(wǎng)頁(yè)格式多40kb。對(duì)于大部分高分辨率的圖像文件來說，這部分?jǐn)?shù)據(jù)并不明顯，但如果想要壓縮圖像文件大小以供網(wǎng)頁(yè)使用，那么這部分就很明顯了。
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