Emailing graphics and the 100kb limit.

[Julian Robinson <>]

It is not actually simple and I hope I can add some clarity to the
problem of email sizes since it causes so much angst.

It is easily possible to manipulate images and save them to be quite
small in terms of kilobytes (KB)  (that is the "size" as
seen by an email program or the space it would take up in storage on a
disk).  Unfortunately it is not so simple to ensure that they
stay small when your email program sends them out into the
ether.

The size of an image in KB is determined by two things - 

1) most obviously, its dimensions (in terms of pixels x pixels which
equates exactly to the size seen on the screen).  So a big image
(all else being equal) is larger in KB than a smaller one, which is
fairly intuitive.

2) less obviously, size in KB is determined by the amount of compression
applied to the image.  All JPG images, which is what we are talking
about, are compressed.  With suitable software you can select how
compressed the image is.  Of course the more compressed you make
it, the worse the visible quality.  Compression is chosen by
photographers and others to be best compromise between quality and
storage size.

The result is that you can have a large image (in dimensions) taking up
the same size in KB as a dimensionally much smaller image, if the large
file is more compressed than the small one.  

eg these two which I am including to clarify discussion...  they are
both the same size in KB - about 12.  (In fact the smaller one is
slightly more KB than the larger.)  But the larger one has been
highly compressed for the sake of the discussion and you can see
compression artifacts, the wiggly lines around the bird.

11.5 KB, high compression low quality (Photoshop quality setting 10 out
of 100)

12.5KB, less compression and higher quality (Photoshop quality setting
50)

To repeat, even though one image is a quarter the size of the other, they
are both about the same size in KB.

This is fine, and it seems that people with the right software can select
the required quality/compression and image size to best present the image
without exceeding the 100KB limit allowed on this list.  Which is
what I thought I did this morning.

I have done some research now, and tested the following theory after
discussing with my tech support...

The problem is that when you EMBED images within the email such as I have
done here (rather than attaching them), the jpg compression which is
applied a second time to the image is chosen by the email program, not by
you.  So this email you are reading, which has two roughly 12KB
images in it and should therefore be about 35KB in total (see below),
will actually reach you at much larger than that - about 120KB. 
This is because my email program (Eudora) embedded my two carefully
prepared images in some way known only to it. Outlook does the
same.

[[[How the 37KB is derived:

11.5 = image 1

12.5 = image 2

2 = text

---------

26 KB total

PLUS an overhead of 30 or 40% required to convert the images to email format, say 26KB +35% = 35 KB.]]]

The point is ---

If you embed images "in-line" within your email, you have no
control over the image size or the email size in KB.
If you attach them, you do have control, and the images will be
transmitted with a resulting size about 35% larger than the size on your
disk, and if you have the right software you can make sure that you
adhere to any agreed limits.

The trouble is that embedding them is much neater and more user-friendly,
so I have no final solution to offer since I prefer embedded
images.  As Martin points out, there is a second problem with
embedded images and that is that people can easily forget to remove the
images from the quoted material when they reply, so the same images go
round and round multiple times.

I hope this is reasonably clear.

Julian


At 11:56 AM 28/08/2007, martin butterfield wrote:
> Geoffrey
> May I assure you that I am well behind you in the queue, despite
> being
> of the  boomer persuasion.  A few thoughts from me. 
> Needless to say I
> am not claiming to be without guilt in the sins being
> considered.
>
> First up, one of the issues with including graphics in the text is
> that if the email system automatically includes the previous text it
> thus automatically includes the images.  I believe it is easier to
> set
> systems not to include attachments so from a basis of minimising the
> volume of transmissions I would suggest that attachments are to be
> preferred to embedded images.
>
> Progressing further down this track it would of course be good if
> everyone considered whether they needed to include all the text of
> every thread they reply to and edited out that which is not
> essential.
>
> A second thought is the discussion group I subscribed to in New York
> (where just about everyone was on really fast broadband with NO
> download limits) did not allow attachments or embedded images at
> all.
> If one wished to send an image (or some other attachment) to the
> group
> one simply put it on a blog and sent round a hyperlink to the
> relevant
> part of the blog.  Both Google and Yahoo provide free blogs that
> seem
> to be quite simple to use.
>
> Martin
>
>
> On 8/28/07, Geoffrey Dabb <> wrote:
> >
> >
> >
> > I, a pre-baby-boomer,  am one of the least expert persons in
> this chatgroup
> > on this matter.  However here are some thoughts.
> >
> >
> >
> > Individual circumstances will vary, between home and work systems,
> and email
> > programs.
> >
> >
> >
> >  If you send a graphic as a separate file, it will go through
> at the
> > original size of the file.  Controlling the size of the overall
> message is a
> > matter of the sender first creating a file of the appropriate
> size.  If you
> > incorporate in the text, other  factors come into play.
> >
> >
> >
> > I think that incorporating the graphic in the text is often better,
> more
> > convenient anyway.
> >
> >
> >
> > I use Office Outlook.  I can read the size of a message in 2
> ways, either in
> > the list panel, or after opening the message under
> 'Properties'.  These
> > readings are usually different for in-text graphics.  Under the
> first,
> > Julian's 'Coastal Birds' message was 315kb, and under the second
> 240kb.
> > Evidently Anthony saved or manipulated the derived graphic
> before
> > reincorporating it, creating a larger file.  On the first read,
> his message
> > was  924kb, and under the second 683kb.  [I am unable to
> comment on the
> > reason for the multiple sendings.]
> >
> >
> >
> > Here are 2 suggestions, apart from the obvious starting with a file
> of the
> > appropriate size.  First, if you are incorporating in the text,
> try reducing
> > the space occupied by the graphic in the message.  I just
> reduced Julian's
> > message to 40kb by doing this.  Secondly, if you are in any
> doubt about the
> > size of a message, try sending it to yourself first.
> >
> >
>
> *******************************************************************************************************