Is the MIME type image jpg the same as image jpeg

Question

Pretty simple question but can t seem to find it anywhere online  I m trying to make a program that depending on the file type will give me the extension

User · Accepted Answer

No  image jpg is not the same as image jpeg  You should use image jpeg  Only image jpeg is recognised as the actual mime type for JPEG files  See https   tools ietf org html rfc3745  https   www w3 org Graphics JPEG    Serving the incorrect Content-Type of image jpg to IE can cause issues  see http   www bennadel com blog 2609-internet-explorer-aborts-images-with-the-wrong-mime-type htm

User · Answer

The important thing to note here is that the mime type is not the same as the file extension  Sometimes  however  they have the same value   https   www iana org assignments media-types media-types xhtml includes a list of registered Mime types  though there is nothing stopping you from making up your own  as long as you are at both the sending and the receiving end  Here is where Microsoft comes in to the picture   Where there is a lot of confusion is the fact that operating systems have their own way of identifying file types by using the tail end of the file name  referred to as the extension  In modern operating systems  the whole name is one long string  but in more primitive operating systems  it is treated as a separate attribute   The OS which caused the confusion is MSDOS  which had limited the extension to 3 characters  This limitation is inherited to this day in devices  such as SD cards  which still store data in the same way   One side effect of this limitation is that some file extensions  such as  gif match their Mime Type  image gif  while others are compromised  This includes image jpeg whose extension is shortened to  jpg  Even in modern Windows  where the limitation is lifted  Microsoft never let the past go  and so the file extension is still the shortened version   Given that that    File Extensions are not File Types Historically  some operating systems had serious file name limitations Some operating systems will just go ahead and make up their own rules   The short answer is    Technically  there is no such thing as image jpg  so the answer is that it is not the same as image jpeg    That won   t stop some operating systems and software from treating it as if it is the same   While we   re at it      Legacy versions of Internet Explorer took the liberty of uploading jpeg files with the Mime Type of image pjpeg  which  of course  just means more work for everybody else  They also uploaded png files as image x-png

User · Answer

tl dr the  quot standards quot  are a hodge-podge mess  it depends who you ask  Overall  there appears to be no MIME type image jpg   Yet  in practice  nearly all software handles image files named  quot   jpg quot  just fine  This particular topic is confusing because the varying association of file name extension associated to a MIME type depends which organization created the table of file name extensions to MIME types   In other words  file name extension  jpg could be many different things  For example  here are three  quot complete lists quot  and one RFC that with varying JPEG Image format file name extensions and the associated MIME types   sitepoint com mime-types-complete-list  archived    jfif   jfif-tbnl   jpe   jpeg   jpg   image jpeg  jfif   jpe   jpeg   jpg   image pjpeg   freeformatter com mime-types  archived    jpeg   jpg    image jpeg  jpeg   jpg    image x-citrix-jpeg  pjpeg   image pjpeg   IANA  quot Media Types quot   formerly known as MIME types  lists  archived   this document lists  quot names quot   not  quot file name extensions quot    jpg not mentioned jpeg   see RFC 2045  no mention   see RFC 2046   image jpeg13 JPEG   video JPEG jpeg2000   video jpeg2000 jpm   image jpm  JPEG 2000  jpx   image jpx  JPEG 2000  vnd sealedmedia softseal jpg    image vnd sealedmedia softseal jpg   RFC 3745 MIME Type Registrations for JPEG 2000  ISO IEC 15444    jpg file extension not mentioned  jpeg file extension not mentioned  jp2   jpg2   image jp2  JPEG 2000 9  jpf   jpx   image jpx  JPEG 2000 ISO-JPEG2000-2 encoded image data 10  mj2   mjp2    video mj2  Motion JPEG 2000 11  jpm   jpgm   image jpm  JPEG 2000 profiles and extensions 12    These  quot complete lists quot  and RFC do not have MIME type image jpg   But for MIME type image jpeg some lists do have varying file name extensions   jpeg   jpg         Other lists do not mention image jpeg  Also  there are different types of JPEG Image formats  e g  Progressive JPEG Image format  JPEG 2000  etcetera  and  quot JPEG Extensions quot  that may or may not overlap in file name extension and declared MIME type  Another confusing thing is RFC 3745 does not appear to match IANA Media Types yet the same RFC is supposed to inform the IANA Media Types document  For example  in RFC 3745  jpf is preferred file extension for image jpx but in IANA Media Types the name jpf is not present  and that IANA document references RFC 3745    Another confusing thing is IANA Media Types lists  quot names quot  but does not list  quot file name extensions quot   This is on purpose  but confuses the endeavor of mapping file name extensions to MIME types  Another confusing thing  is it  quot mime quot   or  quot MIME quot   or  quot MIME type quot   or  quot mime type quot   or  quot mime type quot   or  quot media type quot     The most official seeming document by IANA is surprisingly inadequate  No MIME type is registered for file extension  jpg yet there exists the odd vnd sealedmedia softseal jpg  File extension JPEG is only known as a video type while file extension  jpeg is an image type  when did lowercase and uppercase letters start mattering      At the same time  jpeg2000 is type video yet RFC 3745 considers JPEG 2000 an image type   The IANA list seems to cater to company-specific jpeg formats  e g  vnd sealedmedia softseal jpg    In summary    Because of the prior confusions  it is difficult to find an industry-accepted canonical document that maps file name extensions to MIME types  particularly for the JPEG Image File Format    Related question  quot List of ALL MimeTypes on the Planet  mapped to File Extensions  quot

User · Answer

For those it might help  I use this list as a reference to define my content-type when I have to deal with images on my app   It says that jpg extension can be declared with Content-type   image jpeg   There isn t any image jpg attribute for content-type

[file] Is the MIME type 'image/jpg' the same as 'image/jpeg'?

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