Я делал так (это кусок компонента):
ifPicture.Graphic is
TJPegImage then
begin
bs:=TBlobStream.Create(TBlobField(Field),bmWrite); Picture.Graphic.SaveToStream(bs); bs.Free; end
else
if
Picture.Graphic is
TBitmap then
begin
Jpg:=TJPegImage.Create; Jpg.CompressionQuality:=...; Jpg.PixelFormat:=...; Jpg.Assign(Picture.Graphic); Jpg.JPEGNeeded; bs:=TBlobStream.Create(TBlobField(Field),bmWrite); Jpg.SaveToStream(bs); bs.Free; Jpg.Free; end
else
Field.Clear;