Tech Handbook: A Guide to Efficient JPG/JPEG Creation

A Guide to Efficient JPG/JPEG Creation
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DonaldG on 04/06/2009 05:55:00
 
A Guide to Efficient JPG/JPEG Creation
Images for inclusion with articles
This is not a definitive ‘How To’; rather a few notes and some guidance for
newcomers to the Article Section to keep in mind. None of the pointers are hard
& fast rules. They are for guidance. For the novice to imagery, they are a good
starting point.
General note:
When submitting an article for consideration of publication, images help to
make the piece more interesting. Please feel free to add any photographs, screen
grabs, graphics and drawings that you feel help to illustrate a point.
Although there is an image size limitation for the final publication do not
overly worry if your image exceeds that size. A member of the Articles Team will
adjust it to the final size. If you have the appropriate software to downsize
the image, then by all means do so keeping to the dimensions below. If you are
not sure, submit the large one and leave the rest to us.
Image quality 1:
Quality of image is very important.
Black & white or colour, it doesn’t matter. Photographs should be in focus,
not too light or dark. However, we can often improve & enhance photographs are
outside the quality parameters, so please submit them anyway - we will get back
to you if there are any problems.
Fig.1 Too light
Fig.2 Too dark
Fig.3 Fuzzy - out of focus
Sketches and drawings should be as ‘clean’ as possible. However if the
background is patchy, yellowy, dirty background or otherwise imperfect, again
please submit it - we have ways of cleaning up most images. If we can’t we
will let you know
Image quality 2:
Most imaging software can or will compress the image file to a lesser or
greater degree when it is saved. This compression actually removes bits of data
from the image file and if it is set for low compression (high quality, large
file) then the visible effect is un-noticeable. If the compression is set too
high (Low quality, small file), compression artefacts start to become visible
and detract from the picture.
Artifacts:
Fig.4 This image, x4 enlarged, show distortion artifacts.
A) The spawn looking artifacts, often called JPG artifacts, are caused by
compression processes when the image is saved.
If you are using Paintshop Pro or Photoshop Elements or Photoshop, then you can
set the compression amount very easily. Picasa by Google has fixed compression
that cannot be altered. For any other software, please see below.
Setting the compression levels:
Setting the compression levels in Photoshop and Paintshop Pro is done during
the Save or Save As procedure. The methods are described below.
Photoshop and Photoshop Elements:
Level 10 is ideal for .jpg (12 being the maximum quality.)
Fig.5 In the file menu, select either Save or Save As
Fig.6 After giving the file a name, click on Save as indicated. Another box
will popup.
Fig.7 Either type 10 in the box or use the slider to set 10 in the quality box.
Then press OK. That is all there is to it.
Paintshop Pro:
Level 10 (1 being the maximum quality)
Fig.8 In the file menu, select either Save or Save As
Fig.9 Press the Options button.
Fig.10 Now either type 10 in the quality box or use the slider to set 10. Then
press OK.
Alternative software Save As guidance.
The author is indebted to Zazula for information regarding the alternative
software details
IrfanView
When one selects Save As... from the File menu, and in the Save as type box the
JPG/JPEG format is selected, then an additional box containing the JPG save
options opens:
Fig.11 The quality level is expressed on a 0-100 scale, where 100 stands for
the top quality (uncompressed picture). Move the slider to at least 80 or, even
better, 90.
Microsoft Office Picture Manager
When one selects Export... from the File menu, and in the Export with this file
format box the JPEG format is selected, then there is a link beneath that box
that invokes the JPEG options... dialog box:
Fig.12 In the JPEG options... dialog box that opens, you will need to click the
Select a custom compression setting bullet, and then either move the slider or
directly type the number on a 0-100 scale that corresponds to the desired
quality level (100 being the top quality, with no compression). The approach
here is identical to that one in IrfanView (although you need to select Export
rather than Save as in order to do this):
Fig.13
Corel Photo-Paint
Corel Photo-Paint is part of the CorelDRAW suite. When one selects Save as...
from the File menu, and in the Files of type box the JPG format is selected,
then (as soon as Save is clicked) an additional box containing the JPEG Export
options opens:
Fig.14
Beware because here the compression, rather than the quality, level is selected
- so a bigger number leads to higher compression (and thus to loss of quality).
An extremely useful feature of this program is that, if you click Preview on the
bottom left corner, you see in real-time both the resulting image quality and
the target file size of the new JPG picture:
Fig.15 The result of selecting a far too great a compression is some rather
nasty 'jpg artifacts'. Not desirable!
MS Paint
Not recommended for manipulating photographs, especially if those photographs
are for eventual publication in a TSF article. It is a rudimentary imaging
software more directed at the folk who want to have a play or do some elementary
sketches.
There are 2 methods of resizing an image. Images>Resize/Skew and
Image>Attributes. Neither is satisfactory for precise work without losing the
aspect ratio.
The amount of compression when saving a photograph is fixed. A photograph of
known quality was saved and then reopened. The jpg artefacts were just
detectable with a very critical eye. This would be OK but with the lack of
minimum manipulation features, it is best not to use it for these purposes.
Image types:
For uploading into the ‘Articles for Review’ you may use any of the
following formats:
.bmp .gif .jpe .jpeg .jpj .png & .psd
Unless you have a specific reason for using the other formats, we would prefer
.jpg or .gif
Generally, the rule of thumb is to use .jpg for photographs, drawings or
sketches. .gif is used for images that have solid colours like icons etc. If in
doubt you can use .jpg and we can do any format conversions that may be needed.
If & when your article is published, any image over 625 pixels wide will be
resized.
Copyright:
This is a very important subject. Before you upload any image, sketch or
drawing, you must be either the copyright holder or have written permission from
the copyright holder to use. Because an image is freely available on Internet do
not assume it is ‘public domain’. Indeed, it is safer to assume it IS
copyright & you must check.
In most countries, copyright is automatically deemed to belong to the creator
of the work. There is neither need nor any agency to ‘register’ copyright.
In the UK, copyright extends through to 70 years after the death of the author.
A rule of thumb on figuring if you have copyright ownership. If you created the
image or work, it is reasonably safe to assume you own the copyright. Caveat: If
you were paid or commissioned to create an image or work, then the copyright may
possibly belong to the payer/commissioner. Also, if you created the work during
the the time you worked for an employer, the copyright possibly belongs to the
employer. If in doubt, ask permission to use it. If you are still not sure about
the copyright issues, please contact a member of the TSF Articles team detailing
the issue. We will advise.
Watermarking:
TSF works and images have been plagiarised by other entities on Internet. All
images and works will be marked with the copyright symbol, followed by the year,
followed by www.techsupportforum.com. (See the bottom right corner of the above
images.)
This watermarking serves to be a reminder and deterrent to potential data
thieves.
If you have any problems or queries, do not hesitate to contact any member or
the Articles Team.
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