Update February 5th, 2005
DOWNLOAD ASP v2.0

This is a set of ASP functions for reading EXIF header data (metadata) from JPEG (.JPG) and TIFF (.TIF) files.

Thank you to Mike Trinder who has done a pretty thorough rewrite of the code and added many nice new features. This is now a sourceforge project. If you would like to contribute then please visit the project pages @ http://sourceforge.net/projects/aspexiffuncs/. Version 2.0 is not backwardly compatible to the function calls from 1.0. Do not overwrite your version 1.x functions_exif.asp until you understand the changes that need to be made.

History

Ryan Vettese:
I had figured out a while ago that it was possible to do binary reads on files in ASP. The idea to convert the binary JPEG header data to HEX was lifted from a script written by Lewis Moten. His script can be found here: http://www.lewismoten.com/Items/File/Zip.asp?ItemID=131. At this point I figured all I would need to get out the Exif data was a specification on the format and a couple hours to do some HEX parsing. I was wrong. Exif data is messy and hard to work with. I did manage to find someone out there who was smarter than me though: The main chunk of code to parse the Exif header comes from Jeremy Waite's Exif reader class/dll for VB 6 found here: http://sourceforge.net/projects/exifclass/. I had to do a lot of converting of his ideas because VB6 and ASP are not the same. Big headache.

Mike Trinder
On my timings, this reads a 22Mb TIFF in around 4 seconds, and a 1.5Mb JPEG in 0.22 seconds. The timing is most affected by how much of the file you need to wind through to reach the EXIF data - JPEGs are fast as this tends to be at the start of the file, the TIFF in question has the entire RAW image before the EXIF data. Moving the file pointer to the EXIF area takes about 3.7 seconds...

If you run across any JPEG images that make this script die a painful death then contact Ryan Vettese here.

Changes
Mike Trinder - 2005/02/03
* thorough rewrite to deal with TIFFs as well as JPEGs
* More efficient IFD reading
* File read buffering
* corrected decoding of inline Undefined format
* More efficient byte order checking
* removed dependance on global variables. Now only file buffer is declated by this include
* Utility functions to read Fstop, Shutter Speed, Date and focallength from EXIF
* More value descriptions added
* IFD number added to IFDdirectory to aid distinguishing between thumbnail and main image in TIFF (not actually used yet though)

TODO
* Process MakerNote for various cameras - some formats here: http://park2.wakwak.com/~tsuruzoh/Computer/Digicams/exif-e.html
* Merge EXIF directories from two images
* Save updated EXIF to image
* Return thumbnail data as image

* Support for more image formats?

This sample image is a JPEG of Times Square in New York City taken on my Canon G3.

Date Time: 10/1/2003 9:22:10 PM
Exif Image Width: 341
Exif Image Height: 454
FStop: 4
Shutter: 1/318s
Focal Length: 7.1875mm

IFD #	#	Tag HEX	Tag Name	Format	Size	Offset	Value	Value Described
0	0	010E	Image Description	2	25	170	The Description Field...
0	1	010F	Camera Make	2	6	195	Canon
0	2	0110	Camera Model	2	19	201	Canon PowerShot G3
0	3	0112	Orientation	3	1		1	Normal
0	4	011A	X Resolution	5	1	220	180/1
0	5	011B	Y Resolution	5	1	228	180/1
0	6	0128	Resolution Unit	3	1		2	inch
0	7	0131	Software	2	28	236	ACD Systems Digital Imaging
0	8	0132	Date Time	2	20	264	2003:10:01 21:22:10	10/1/2003 9:22:10 PM
0	9	013B	Artist	2	7	284	Ryan V
0	10	0213	YCbCr Positioning	3	1		1
0	11	8298	Copyright	2	5	291	2003
0	12	8769	Exif Offset	4	1		296
0.1	13	829A	Exposure Time	5	1	686	1/320
0.1	14	829D	FStop	5	1	694	40/10
0.1	15	9000	Exif Version	7	4		0210	2.10
0.1	16	9003	Date Time Original	2	20	702	2003:08:25 08:48:54	8/25/2003 8:48:54 AM
0.1	17	9004	Date Time Digitized	2	20	722	2003:08:25 08:48:54	8/25/2003 8:48:54 AM
0.1	18	9101	Components Configuration	7	4		
0.1	19	9102	Compressed Bits Per Pixel	5	1	742	5/1
0.1	20	9201	Shutter Speed Value	10	1	750	266/32
0.1	21	9202	Aperture Value	5	1	758	128/32
0.1	22	9204	Exposure Bias Value	10	1	766	0/3
0.1	23	9205	Max Aperture Value	5	1	774	64/32
0.1	24	9207	Metering Mode	3	1		5	Multi-segment
0.1	25	9209	Flash	3	1		24	Undefined
0.1	26	920A	Focal Length	5	1	782	230/32
0.1	27	927C	Maker Note	7	606	790	
0.1	28	9286	User Comment	7	19	1404	Crazy Times Square
0.1	29	9290	Subsec Time	2	4		156
0.1	30	A000	Flash Pix Version	7	4		0100	1.00
0.1	31	A001	Color Space	3	1		1	sRGB
0.1	32	A002	Exif Image Width	4	1		341
0.1	33	A003	Exif Image Height	4	1		454
0.1	34	A005	Exif Interoperability Offset	4	1		1423
0.1	35	A20E	Focal Plane X Resolution	5	1	1453	2272000/280
0.1	36	A20F	Focal Plane Y Resolution	5	1	1461	1704000/210
0.1	37	A210	Focal Plane Resolution Unit	3	1		2	inch
0.1	38	A217	Sensing Method	3	1		2
0.1	39	A300	File Source	7	1		
0.1	40	A401	A401	3	1		0
0.1	41	A402	A402	3	1		0
0.1	42	A403	A403	3	1		0
0.1	43	A404	A404	5	1	1469	2272/2272
0.1	44	A406	A406	3	1		0
1	45	0103	Compression	3	1		6	JPEG
1	46	0201	JPEG Interchange Format	4	1		1519
1	47	0202	JPEG Interchange Format Length	4	1		4723

This sample image is a NON Intel saved JPEG file format (maybe Mac OS?).

Date Time: 4/20/2004 10:07:58 PM
Exif Image Width: 640
Exif Image Height: 480
FStop: 2
Shutter: 1/60s
Focal Length: 7.13mm

IFD #	#	Tag HEX	Tag Name	Format	Size	Offset	Value	Value Described
0	0	010F	Camera Make	2	6	146	CASIO
0	1	0110	Camera Model	2	10	152	QV-5700
0	2	0112	Orientation	3	1		1	Normal
0	3	011A	X Resolution	5	1	162	72/1
0	4	011B	Y Resolution	5	1	170	72/1
0	5	0128	Resolution Unit	3	1		2	inch
0	6	0131	Software	2	20	178	Adobe Photoshop 7.0
0	7	0132	Date Time	2	20	198	2004:04:20 22:07:58	4/20/2004 10:07:58 PM
0	8	0213	YCbCr Positioning	3	1		1
0	9	C4A5	C4A5	7	40	218	PrintIM
0	10	8769	Exif Offset	4	1		260
0.1	11	829A	Exposure Time	5	1	614	16666/1000000
0.1	12	829D	FStop	5	1	622	20/10
0.1	13	8822	Exposure Program	3	1		2
0.1	14	9000	Exif Version	7	4		0220	2.20
0.1	15	9003	Date Time Original	2	20	630	2003:04:19 18:40:14	4/19/2003 6:40:14 PM
0.1	16	9004	Date Time Digitized	2	20	650	2003:04:19 18:40:14	4/19/2003 6:40:14 PM
0.1	17	9101	Components Configuration	7	4		
0.1	18	9102	Compressed Bits Per Pixel	5	1	670	19293792/4915200
0.1	19	9204	Exposure Bias Value	10	1	678	0/6
0.1	20	9205	Max Aperture Value	5	1	686	20/10
0.1	21	9207	Metering Mode	3	1		5	Multi-segment
0.1	22	9208	Light Source	3	1		0
0.1	23	9209	Flash	3	1		25	Undefined
0.1	24	920A	Focal Length	5	1	694	713/100
0.1	25	A000	Flash Pix Version	7	4		0100	1.00
0.1	26	A001	Color Space	3	1		1	sRGB
0.1	27	A002	Exif Image Width	4	1		640
0.1	28	A003	Exif Image Height	4	1		480
0.1	29	A300	File Source	7	1		
0.1	30	A401	A401	3	1		0
0.1	31	A402	A402	3	1		0
0.1	32	A403	A403	3	1		0
0.1	33	A404	A404	5	1	702	65536/65536
0.1	34	A405	A405	3	1		34
0.1	35	A406	A406	3	1		0
0.1	36	A407	A407	3	1		0
0.1	37	A408	A408	3	1		0
0.1	38	A409	A409	3	1		2
0.1	39	A40A	A40A	3	1		0
1	40	0103	Compression	3	1		6	JPEG
1	41	011A	X Resolution	5	1	790	72/1
1	42	011B	Y Resolution	5	1	798	72/1
1	43	0128	Resolution Unit	3	1		2	inch
1	44	0201	JPEG Interchange Format	4	1		806
1	45	0202	JPEG Interchange Format Length	4	1		5154