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 Siren Tiger Home Page::ST-Zone::Ramblings::Ramble #54
Can you tell the difference in these two images? Date: 2008-01-25 || <<Previous Ramble<<
Can you tell the difference?

Can you tell the difference between these two images?

Image 1

Click on image to see original image (3072px x 2304px: 1.5 Mb)
alaska

Full-sized original:
  • FileName: DSC01100.JPG
  • FileDateTime: 1201242575
  • FileSize: 1560831
  • FileType: 2
  • MimeType: image/jpeg
  • SectionsFound: ANY_TAG, IFD0, THUMBNAIL, EXIF, INTEROP
  • COMPUTED:
    • html: width="3072" height="2304"
    • Height: 2304
    • Width: 3072
    • IsColor: 1
    • ByteOrderMotorola: 0
    • ApertureFNumber: f/5.6
    • Thumbnail.FileType: 2
    • Thumbnail.MimeType: image/jpeg
  • ImageDescription:
  • Make: SONY
  • Model: DSC-H5
  • Orientation: 1
  • XResolution: 72/1
  • YResolution: 72/1
  • ResolutionUnit: 2
  • DateTime: 2007:07:04 15:20:29
  • YCbCrPositioning: 2
  • Exif_IFD_Pointer: 256
  • UndefinedTag:0xC4A5: PrintIM0300
  • THUMBNAIL:
    • Compression: 6
    • Make: SONY
    • Model: DSC-H5
    • Orientation: 1
    • XResolution: 72/1
    • YResolution: 72/1
    • ResolutionUnit: 2
    • DateTime: 2007:07:04 15:20:29
    • JPEGInterchangeFormat: 2952
    • JPEGInterchangeFormatLength: 10545
  • ExposureTime: 10/3200
  • FNumber: 56/10
  • ExposureProgram: 8
  • ISOSpeedRatings: 125
  • ExifVersion: 0221
  • DateTimeOriginal: 2007:07:04 15:20:29
  • DateTimeDigitized: 2007:07:04 15:20:29
  • ComponentsConfiguration: 
  • CompressedBitsPerPixel: 4/1
  • ExposureBiasValue: 0/10
  • MaxApertureValue: 48/16
  • MeteringMode: 3
  • LightSource: 0
  • Flash: 0
  • FocalLength: 60/10
  • FlashPixVersion: 0100
  • ColorSpace: 1
  • ExifImageWidth: 3072
  • ExifImageLength: 2304
  • InteroperabilityOffset: 2746
  • FileSource: 
  • SceneType: 
  • CustomRendered: 0
  • ExposureMode: 0
  • WhiteBalance: 0
  • SceneCaptureType: 1
  • Contrast: 0
  • Saturation: 0
  • Sharpness: 0
  • InterOperabilityIndex: R98
  • InterOperabilityVersion: 0100
 Above smaller (512px x 384px: 167 kb) version of the original:
  • FileName: DSC01100_small.jpg
  • FileDateTime: 1201233019
  • FileSize: 170709
  • FileType: 2
  • MimeType: image/jpeg
  • SectionsFound: ANY_TAG, IFD0, THUMBNAIL, EXIF
  • COMPUTED:
    • html: width="512" height="384"
    • Height: 384
    • Width: 512
    • IsColor: 1
    • ByteOrderMotorola: 0
    • ApertureFNumber: f/5.6
    • Thumbnail.FileType: 2
    • Thumbnail.MimeType: image/jpeg
  • ImageDescription:
  • Make: SONY
  • Model: DSC-H5
  • Orientation: 1
  • XResolution: 72/1
  • YResolution: 72/1
  • ResolutionUnit: 2
  • Software: Adobe Photoshop 7.0
  • DateTime: 2008:01:24 18:31:11
  • YCbCrPositioning: 2
  • UndefinedTag:0xC4A5: PrintIM0300
  • Exif_IFD_Pointer: 288
  • THUMBNAIL:
    • Compression: 6
    • XResolution: 72/1
    • YResolution: 72/1
    • ResolutionUnit: 2
    • JPEGInterchangeFormat: 814
    • JPEGInterchangeFormatLength: 2728
  • ExposureTime: 10/3200
  • FNumber: 56/10
  • ExposureProgram: 8
  • ISOSpeedRatings: 125
  • ExifVersion: 0221
  • DateTimeOriginal: 2007:07:04 15:20:29
  • DateTimeDigitized: 2007:07:04 15:20:29
  • ComponentsConfiguration: 
  • CompressedBitsPerPixel: 4/1
  • ExposureBiasValue: 0/10
  • MaxApertureValue: 48/16
  • MeteringMode: 3
  • LightSource: 0
  • Flash: 0
  • FocalLength: 60/10
  • FlashPixVersion: 0100
  • ColorSpace: 1
  • ExifImageWidth: 512
  • ExifImageLength: 384
  • FileSource: 
  • SceneType: 
  • CustomRendered: 0
  • ExposureMode: 0
  • WhiteBalance: 0
  • SceneCaptureType: 1
  • Contrast: 0
  • Saturation: 0
  • Sharpness: 0

Image 2

Click on image to see full-sized version: (3072px x 2304px: 459 kb)
alaska

Full-sized version:
  • FileName: photo.jpg
  • FileDateTime: 1201242636
  • FileSize: 469839
  • FileType: 2
  • MimeType: image/jpeg
  • SectionsFound: COMMENT
  • COMPUTED:
    • html: width="3072" height="2304"
    • Height: 2304
    • Width: 3072
    • IsColor: 1
  • COMMENT:
Above smaller (512px x 384px: 22 kb) version of the original:
  • FileName: web.jpg
  • FileDateTime: 1201233020
  • FileSize: 23024
  • FileType: 2
  • MimeType: image/jpeg
  • SectionsFound: COMMENT
  • COMPUTED:
    • html: width="512" height="384"
    • Height: 384
    • Width: 512
    • IsColor: 1
  • COMMENT:

Can you tell the difference? I certainly can't! Image 1 (original) is the original file my digital camera made, and Image 1 (above) is a smaller version produced by changing the image size with PhotoShop. Image 2, both the full-sized and the web-sized versions, were made using the PHP module::GD. GD simply read the photograph's jpeg information (whatever that is) and then copied the info into new files (one with the full-sized dimensions and the other with web-sized dimensions).

Now what I wonder just what is all the extra information in the original photograph file that makes it whoppin' a Megabyte and half whereas the GD reproduction (which supposedly has all the image data albeit none of the extra "meta" data) is only one third the size. I have no idea. It's possible the GD reproduction has limitations and its versions are poorer in quality (although I can't see any difference). Or it's possible the raw camera data is massive compared to the displayed jpeg data (which is compressed, after all) but stored in jpeg image as well. (After all, one wants all the camera information in the file.) But if that were the case why does PhotoShop's "Save for Web" option result in a file equally large?

It's intriguing. I wish I knew more about it.
Siren Tiger Enterprises is the working name for Nathaniel Meyers, a web programmer experienced in all aspects of web technology and specialized in interactive dynamic content.
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