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A 1911 Commemorative,
and ''Image Burden'' -
Let's just look at one firearm's picture and make some
observations. The original photograph was taken on a
Kodak DX6340 3.1 Mega Pixel camera - giving an original
of 2031 x 1524 pixels, at 230 DPI. This
would equate to a print size in inches of 8.8"
x 6.6" .... large enough for most purposes, tho
a reduction in DPI or, a higher MegaPixel figure would
achieve an 8 x 10 probably. Lighting was primarily fluorescent
almost over head, with a small amount of tungsten fill-in..
Let's tho be more concerned with displaying on the THR.
So - this pic is way too large, both physically in pixels
and as a file, even with strong JPG compression. Quality
is quite good but - we have to reduce it to some more
reasonable level.
I personally consider that it is adequate to show a
picture with a max dimension not exceeding 600
pixels (I know - many don't agree!!), which avoids scrolling
off on the horizontal for those not on high resolution
monitor screens. This one is slightly cropped and compressed
to about 10:1, giving a file size around 56k
..... good for download speed. |
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So -
this picture is now, 550 x 347 (230 DPI), after
cropping and reduction (linear interpolation), and saved
at a compression of 10:1 yielding a file size
of about 56k (after decompression, about 600k
in memory). Agreed, some resolution is lost but it shows
enough IMO to serve a purpose... although restricted
to 550 here because of layout limitations .....
600 would be just that bit better and filesize
perhaps then nearer 70k ..... still not too bad.
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Let us now though just look at a portion from the
original ..........
This is sampled as a 550 x 413 from the 2031
x 1524 original, it is showing the definition
at max. Nice, but impractical to use full size.
Thus the reduction process we saw in the first image.
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One further interesting comparison though ....
is to take a similar sample from the reduced
image, and enlarge back to ''original'' size....
Notice now how, predictably, resolution has
diminished a lot. If however we reduced that
back down to the scale in the top picture ....
and look at it within that image - it in fact
looks passable, because of the ''averaging''
effect when viewed at that scale. A compromize
for sure but, still conveying useful information.
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''Image
Burden'', some figures -
Let me just mention some figures regarding
''image page burden''. Say you have
a page of 20 posts and each one has
one image ..... if all those images
are large to the tune of 800 pixel or
even bigger, then apart from some chance
of scrolling horizontally being required,
filesizes could well be in the region
of 150k to 200k each. Thus an image
download burden of about 3Mb to 4Mb
....... considerable for dial up people,
even if quality is good.
Now relate the same to where all images
were around 50k. What then? The max
image burden would be about 1Mb!! Still
will need some waiting to see them all,
unless some were cached earlier, but
much more bearable!
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Ok,
perhaps by now you are well saturated!!
I hope though you are beginning
to see some of the relationships
between the various elements of
the image process and what sizes
can work best.
Go look at another extra
page dealing with similar
aspects .... showing various sizes
of my favorite .454 muzzle flash
pic', and some data.
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