iphone - iPhone JPG 图像有非标准的魔术字节 ff d8 ff e1？

Question

在接受上传的图像之前，我的网络应用程序会根据文件扩展名检查前四个字节。一位同事向我展示了他的 iPhone 中被拒绝的图像。它们具有不同的第四个字节（e1 = 225 而不是预期的 e0 = 224）。

这对 iPhone 来说很常见吗？JPG 文件中是否使用了其他可能的魔术字节字符串？

编辑：找到这个有用的列表：http ://www.garykessler.net/library/file_sigs.html

score 6 · Accepted Answer

它们似乎以某种方式表示 JPEG 的一个子类别。我发现 FF D8 FF E0 魔术表示“JFIF JPEG”，而 FF D8 FF E1 表示“EXIF JPEG”。

编辑：在谷歌缓存中找到这个：http: //tinyurl.com/ydtjpjw（有趣，因为它表明三星还有更多变体）

score 3 · Accepted Answer

FF 总是标识一个“标记” - 由于我目前正在编写一个 javascript 文件标识符，我将尝试用我的 JPEG javascript 对象来回答......

已经给出了基本答案（已接受的答案），但这更详细地说明了如何检查不同的 App 标记（带有后备）。顺便说一句：到目前为止，JFIF、EXIF、Adobe、佳能和三星都有特殊的 APP0（但我们不知道未来）。所以js对象的逻辑是：

如果其中一个 SPECS[x].regex 匹配，则它获胜（第一个获胜）。但如果没有匹配，则父对象（仅 FFd8）获胜。

SPECS 对象根据 PRONOM 标识符提供- 您可以像这样查看它们

' http://apps.nationalarchives.gov.uk/pronom/fmt/ '.concat(PUID) [官方] ' http://apps.nationalarchives.gov.uk/pronom/x-fmt/ '.concat(xPUID ) [实验性]

_FFD8: { 
    SPECS: [
        { 
            PUID: 112, 
            regex: /^FFD8FFE8(.{2})53504946460001/, 
            desc: 'jpeg: Still Picture Interchange Format file (SPIF)',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                version: '1.00'
            }
        }, 
        { 
            PUID: 44, 
            regex: /^FFD8FFE0(.{2})4A464946000102/, 
            desc: 'jpeg: JPEG File Interchange Format file (JFIF), v. 1.02',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                version: '1.02',
            }
        },
        { 
            PUID: 43, 
            regex: /^FFD8FFE0(.{2})4A464946000101/, 
            desc: 'jpeg: JPEG File Interchange Format file (JFIF), v. 1.01',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                version: '1.01',
            }
        },
        { 
            PUID: 42, 
            regex: /^FFD8FFE0(.{2})4A464946000100/, 
            desc: 'jpeg: JPEG File Interchange Format file (JFIF), v. 1.00',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                version: '1.00',
            }
        },          
        { 
            PUID: 41, 
            xPUID: 398,
            regex: /^FFD8FFE1(.{2})45786966000049492A00(.+)009007000400000030323030/, 
            desc: 'jpeg: JPG Image File, using Exchangeable Image File Format (Exif), little endian, v. 2.0',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                endian: 'little',
                version: '2.0',
            }
        }, 
        { 
            PUID: 41, 
            xPUID: 398, 
            regex: /^FFD8FFE1(.{2})4578696600004D4D002A(.+)900000070000000430323030/, 
            desc: 'jpeg: JPG Image File, using Exchangeable Image File Format (Exif), big endian, v. 2.0',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                endian: 'big',
                version: '2.0',
            }
        },              
        { 
            PUID: 41, 
            xPUID: 390,
            regex: /^FFD8FFE1(.{2})45786966000049492A00(.+)009007000400000030323130/, 
            desc: 'jpeg: JPG Image File, using Exchangeable Image File Format (Exif), little endian, v. 2.1',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                endian: 'little',
                version: '2.1',
            }
        }, 
        { 
            PUID: 41, 
            xPUID: 390, 
            regex: /^FFD8FFE1(.{2})4578696600004D4D002A(.+)900000070000000430323130/, 
            desc: 'jpeg: JPG Image File, using Exchangeable Image File Format (Exif), big endian, v. 2.1',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                endian: 'big',
                version: '2.1',
            }
        },          
        { 
            PUID: 41, 
            xPUID: 391,
            regex: /^FFD8FFE1(.{2})45786966000049492A00(.+)009007000400000030323230/, 
            desc: 'jpeg: JPG Image File, using Exchangeable Image File Format (Exif), little endian, v. 2.2',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                endian: 'little',
                version: '2.2',
            }
        }, 
        { 
            PUID: 41, 
            xPUID: 391, 
            regex: /^FFD8FFE1(.{2})4578696600004D4D002A(.+)900000070000000430323230/, 
            desc: 'jpeg: JPG Image File, using Exchangeable Image File Format (Exif), big endian, v. 2.2',
            regexCapture: [
                { key: 'recordedSignature' }, 
                { key: 'segmentLength', fn: function(h){ return { value:parseInt(h, 16), _val:h.toString() }; } }
            ], 
            valueCapture: {
                endian: 'big',
                version: '2.2',
            }
        }, 
        // specific JPEG (all begin with FFD8FF, map them to PUID 41)
        { 
            PUID: 41, 
            regex: /^FFD8FFED/, 
            desc: 'jpeg: JPG Image File, Adobe JPEG, Photoshop CMYK buffer'
        }, 
        { 
            PUID: 41, 
            regex: /^FFD8FFE2/, 
            desc: 'jpeg: JPG Image File, Canon JPEG, Canon EOS-1D'
        }, 
        { 
            PUID: 41, 
            regex: /^FFD8FFE3/, 
            desc: 'jpeg: JPG Image File, Samsung JPEG, e.g. Samsung D500'
        }, 
        { 
            PUID: 41, 
            regex: /^FFD8FFDB/, 
            desc: 'jpeg: JPG Image File, Samsung JPEG, e.g. Samsung D807'
        }
    ],
    ext: ['JPG', 'JPE', 'JPEG', 'SPF', 'SPIFF'],
    signature: [ 255, 216 ],
    desc: 'jpeg: JPEG File Interchange Format file, App0 marker not known',
    mime: 'image/jpeg',
    specifications: [
        { text:'Specification for the JFIF file format', href:'http://www.w3.org/Graphics/JPEG/jfif3.pdf', type:'W3', format:'pdf' },
        { text:'The JPEG compression specification', href:'http://www.w3.org/Graphics/JPEG/itu-t81.pdf', type:'W3', format:'pdf' },
        { text:'Exchangeable image file format for digital still cameras', href:'http://home.jeita.or.jp/tsc/std-pdf/CP3451C.pdf', type:'vendor', format:'pdf' }
    ], 
    references: [
        { text:'JPEG JFIF W3 Info', href:'http://www.w3.org/Graphics/JPEG/', type:'W3', format:'html' },
        { text:'JPEG.org', href:'http://www.jpeg.org/', type:'info', format:'html' },
        { text:'JPEG Exif App markers', href:'http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html', type:'info', format:'html'}
    ]
}

score 2 · Accepted Answer

2

根据 Google的说法，这似乎是一个完全有效的 JPEG 变体。

于 2009-12-29T15:30:32.387 回答

iphone - iPhone JPG 图像有非标准的魔术字节 ff d8 ff e1？

3 回答 3

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