Re: Problem retrieving images from Access 2003 Binary Large Object

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Changing the strings to byte arrays has fixed the problem.

Thanks

--
Paul H.


"bob" wrote:

>
>
> ReadBlob/WriteBlob use string functions, which causes the doubling of size. Eliminate the string functions
> and you will avoid the conversion & extra storage and will be able to work with the data directly in ASP
> as you require.
>
> --
> _______________________________________________________
> http://www.ammara.com/
> Image Handling Components, Samples, Solutions and Info
> DBPix 2.0 - lossless jpeg rotation, EXIF, asynchronous
>
>
>
> =?Utf-8?B?UGF1bCBI?= <PaulH@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> >I can write and read jpeg images to/from MS Access table BLOB fields using
> >the ReadBlob and Write Blob functions recommended in
> >http://support.microsoft.com/?kbid=210486, and the retrieved image can be
> >displayed in an MS access form image field.
> >
> >If I connect to the Access database from an ASP page and read the BLOB field
> >using ADO.NET functions the returned file is twice the size of the file
> >returned when reading the BLOB field using MS Access, and it cannot be
> >displayed.
> >
> >The code for reading the BLOB field is listed below and copied from
> >http://support.microsoft.com/default.aspx?scid=kb;en-us;326502 .
> >
> >Can you suggest what may be causing this problem.
> >
> >
> >
> >Comparing the contents of the two jpeg files returned it appears that each
> >byte in the original file is converted to two bytes when stored in the MS
> >access table. If the data is read back using the MS access WriteBLOB function
> >then each pair of bytes is correctly reconverted back to one byte with the
> >original value.
> >
> >When the BLOB is read from the ASP page this does not happen. I tried
> >removing the most signifant byte of each pair of bytes and creating a file of
> >the original size but the picture could still not be displayed.
> >
> >Further examination of the file contents showed that the most of the least
> >significant bytes of each pair contained the original value but occasionally
> >they did not and there is a value in the most significant byte.
> >
> ><%@ Page Language="VB" Debug="true" ContentType="text/html"
> >ResponseEncoding="iso-8859-1" %>
> ><%@Import Namespace="System.Data" %>
> ><%@Import Namespace="System.IO" %>
> ><%
> >Dim PictureCol As Integer = 0 ' the column # of the BLOB field
> >
> >Dim cn As New OleDbConnection("provider=Microsoft.Jet.OLEDB.4.0;Data
> >Source=C:\Inetpub\wwwroot\PaulsWebASPNet\LakeDistrictFells2000.mdb")
> >
> >Dim cmd As New OleDbCommand("SELECT photo FROM tblPhoto WHERE
> >PhotoNumber=2", cn)
> >
> >cn.Open()
> >
> >Dim dr As OleDbDataReader = cmd.ExecuteReader()
> >dr.Read()
> >
> >Dim b(dr.GetBytes(PictureCol, 0, Nothing, 0, Integer.MaxValue) - 1) As Byte
> > dr.GetBytes(PictureCol, 0, b, 0, b.Length)
> > dr.Close()
> > cn.Close()
> >
> >‘***** start of temporary code ******
> >Dim fs As New
> >System.IO.FileStream("C:\Inetpub\wwwroot\paulsWebaspNet\test2.jpg",
> >IO.FileMode.Create, IO.FileAccess.Write)
> > fs.Write(b, 0, b.Length)
> > fs.Close()
> >‘***** end of temporary code ******
> >
> >'Response.Expires = 0
> >'Response.Buffer = TRUE
> >'Response.Clear
> >'Response.ContentType = "image/jpg"
> >'Response.BinaryWrite(b)
> >'Response.End
> >
> >%>
> >
> >--
> >Paul H.
>
>
.