9 New Messages
Digest #9328
Messages
Sat Jan 12, 2013 10:16 am (PST) . Posted by:
"Dave C" davec2468
>> A friend is having issues connecting with a PC from her iMac. It's a recent (2012) model running Lion.
>> ...
>> Dave
-=-=-=-
> Article on NBC this AM about security with Java.
Charles
-=-=-=-
Is there a cross-platform alternative to GoToMyPC that doesn't use Java?
Thanks,
Dave
>> ...
>> Dave
-=-=-=-
> Article on NBC this AM about security with Java.
Charles
-=-=-=-
Is there a cross-platform alternative to GoToMyPC that doesn't use Java?
Thanks,
Dave
Sat Jan 12, 2013 2:50 pm (PST) . Posted by:
"Dave C" davec2468
"If a train leaves Chicago traveling west..."
A color jpg file is 1.9 MB (Finder says: 1,940,805 bytes); image size: 1024 x 768.
1.9 MB divided by the image size gives something like 2.4, which is not 8 bits per pixel or such.
Why can't I make the numbers agree? I know it must be something simple...
Thanks,
Dave
A color jpg file is 1.9 MB (Finder says: 1,940,805 bytes); image size: 1024 x 768.
1.9 MB divided by the image size gives something like 2.4, which is not 8 bits per pixel or such.
Why can't I make the numbers agree? I know it must be something simple...
Thanks,
Dave
Sat Jan 12, 2013 3:03 pm (PST) . Posted by:
"Chris Jones" bobstermcbob
On 12 Jan 2013, at 10:50pm, Dave C davec2468@yahoo.
> "If a train leaves Chicago traveling west..."
>
> A color jpg file is 1.9 MB (Finder says: 1,940,805 bytes); image size: 1024 x 768.
>
> 1.9 MB divided by the image size gives something like 2.4, which is not 8 bits per pixel or such.
>
> Why can't I make the numbers agree? I know it must be something simple…
data compression …
>
> Thanks,
> Dave
>
> ------------
>
> Group FAQ:
> http://www.macsuppo
>
> Yahoo! Groups Links
>
>
>
[Non-text portions of this message have been removed]
Sat Jan 12, 2013 3:42 pm (PST) . Posted by:
"Dave C" davec2468
>> Why can't I make the numbers agree? I know it must be something simple?
>
> data compression?
-=-=-=-
I guess that must be the answer.
Thanks.
>
> data compression?
-=-=-=-
I guess that must be the answer.
Thanks.
Sat Jan 12, 2013 6:20 pm (PST) . Posted by:
"Jim Saklad" jimdoc01
> A color jpg file is 1.9 MB (Finder says: 1,940,805 bytes); image size: 1024 x 768.
>
> 1.9 MB divided by the image size gives something like 2.4, which is not 8 bits per pixel or such.
>
> Why can't I make the numbers agree? I know it must be something simple...
Well, JPEG is a *lossy* image compression format....
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim Saklad mailto:jimdoc@icloud.com
>
> 1.9 MB divided by the image size gives something like 2.4, which is not 8 bits per pixel or such.
>
> Why can't I make the numbers agree? I know it must be something simple...
Well, JPEG is a *lossy* image compression format....
--
~~~~~~~~~~~~
Jim Saklad mailto:jimdoc@icloud.
Sat Jan 12, 2013 9:17 pm (PST) . Posted by:
"Yahoo" hammilljames2000
Very interesting, thanks.
Could you explain the term lossy? I see often especially in audio... am I correct?
Danny Giguere
On 2013-01-12, at 21:20, Jim Saklad jimdoc@icloud.com > wrote:
> > A color jpg file is 1.9 MB (Finder says: 1,940,805 bytes); image size: 1024 x 768.
> >
> > 1.9 MB divided by the image size gives something like 2.4, which is not 8 bits per pixel or such.
> >
> > Why can't I make the numbers agree? I know it must be something simple...
>
> Well, JPEG is a *lossy* image compression format....
>
> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Jim Saklad mailto:jimdoc@icloud.com
>
>
[Non-text portions of this message have been removed]
Could you explain the term lossy? I see often especially in audio... am I correct?
Danny Giguere
On 2013-01-12, at 21:20, Jim Saklad jimdoc@icloud.
> > A color jpg file is 1.9 MB (Finder says: 1,940,805 bytes); image size: 1024 x 768.
> >
> > 1.9 MB divided by the image size gives something like 2.4, which is not 8 bits per pixel or such.
> >
> > Why can't I make the numbers agree? I know it must be something simple...
>
> Well, JPEG is a *lossy* image compression format....
>
> --
> ~~~~~~~~~~~~
> Jim Saklad mailto:jimdoc@icloud.
>
>
[Non-text portions of this message have been removed]
Sat Jan 12, 2013 9:25 pm (PST) . Posted by:
"Jim Saklad" jimdoc01
> Very interesting, thanks.
> Could you explain the term lossy? I see often especially in audio... am I correct?
> Danny Giguere
Some (variable) portion of the data in the original is absent, missing, lost in the recording.
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jim Saklad mailto:jimdoc@icloud.com
> Could you explain the term lossy? I see often especially in audio... am I correct?
> Danny Giguere
Some (variable) portion of the data in the original is absent, missing, lost in the recording.
--
~~~~~~~~~~~~
Jim Saklad mailto:jimdoc@icloud.
Sun Jan 13, 2013 5:03 am (PST) . Posted by:
"Otto Nikolaus" nikyzf
JPEG is analogous to MP3 in audio. Both are lossy, so some information is
lost in exchange for a greatly reduced file size. The idea is that the loss
is not noticeable except by critical users. In each case, the "quality"
setting is variable so the degree of information loss and file size
reduction is also variable for the same source file.
http://en.wikipedia.org/wiki/Lossy_compression >
Otto
On 13 January 2013 05:17, Yahoo hammilljames2000@yahoo.ca > wrote:
> Very interesting, thanks.
> Could you explain the term lossy? I see often especially in audio... am I
> correct?
>
[Non-text portions of this message have been removed]
lost in exchange for a greatly reduced file size. The idea is that the loss
is not noticeable except by critical users. In each case, the "quality"
setting is variable so the degree of information loss and file size
reduction is also variable for the same source file.
http://en.wikipedia
Otto
On 13 January 2013 05:17, Yahoo hammilljames2000@
> Very interesting, thanks.
> Could you explain the term lossy? I see often especially in audio... am I
> correct?
>
[Non-text portions of this message have been removed]
Sun Jan 13, 2013 7:49 am (PST) . Posted by:
"Denver Dan" denverdan22180
Howdy.
Dave, several responders have suggested that you are seeing the results
of the lossy JPEG file format.
Book Alert! A long reply follows. Only read if interested in the
topic of compressed and lossy file formats.
A JPEG image is a compressed file format. The JPEG compression is a
type that when the JPEG file is saved data is permanently discarded in
order to make the file smaller.
Most software programs, and digital cameras, can be set for different
levels of JPEG compression. Normally you can pick between JPEG levels
of 1 to 10. A JPEG level 1 is very high compression (and high loss of
data) up to a JPEG 10 with low compression (a bigger file) and low data
loss.
Video files, I think nearly all of them, are also compressed. Many
video compression methods are available and these use something called
a Codec (or, Compression/Decompression) method such as MPG4, WMV, or
other.
Music files are also often compressed. A very common audio file is the
MPG which is highly compressed (and lossy). If you look at the import
preferences for iTunes it gives you several different types of RIP file
formats for when you import/RIP an audio CD into iTunes and some are
lossy and some are not. The non lossy music file formats result in
larger music files but usually better audio.
A GIF image file format is also a compressed file format but different
from JPEG. While a JPEG file can contain millions of colors and GIF
file can only have a maximum of 256 colors so a good quality photo that
is saved in GIF format automatically losses all of those colors, hues,
shades. But a GIF file can also be saved with fewer colors. One
reason that GIF is still used is that a GIF file can have just one
color, or just two colors (like a black and white corporate logo) and
this results in a tiny file size that downloads very quickly on a web
page. A GIF file can also be used for other web page tricks such as
files with a transparent background color or an animated GIF file that
appears to be a short movie (it's really a series of images each of
which is slightly altered to mimic motion).
You may see the term CompuServeGIF (in Adobe Photoshop, for example)
because CompuServe originally developed the GIF file format back in the
days of SLOW dialup internet. A legal wrangle over GIF resulted and a
newer file format called PNG was developed. PNG can combine the
flexibility of JPEG and GIF and if used properly can result in small
but high quality compressed images but PNG hasn't really caught on in a
big way.
Professional photogs will shoot pictures in a high quality JPEG file
format but they understand that if they edit and save a JPEG multiple
times it will soon loss so much quality as to become unusable so before
editing they will convert the JPEG to a format like Photoshop's PSD non
lossy high quality format for editing. I keep my Nikon DSLR camera
set at the 300 dpi JPEG file format rather than a lower quality file
format because this works well for quality, for most smaller snap shot
paper sizes (like 4x6 inches) if I want to print, and it means more
images can fit on a hard drive or SD camera card. Of course, if I
picked a 72 dpi JPEG size a LOT more pictures could fit on the SD
camera card but 72 dpi while it will look just fine on screen is just
way too low a resolution for even medium quality printing.
TIFF is used as a good quality and non lossy file format for images for
photo graphics and desktop publishing. TIFF image file format was
initially developed for scanning of photos. Some digital cameras can
be set to make TIFF images. A TIFF image file retains aspects of the
original photograph's limits such as it must be a square or rectangle
image. TIFF images can also be compressed but the technique is not a
lossy compression
ESP is another image format. Mostly used by professionals these days.
ESP, meaning Encapsulated PostScript, offers some fun tricks for those
who would like to work in programs like Adobe Photoshop to achieve some
nifty results on paper. An ESP can be any shape, can have transparent
parts, and other effects. For example, if you spend a few minutes in
Photoshop learning to create a clipping path (see Clipping Mask in
recent versions of Photoshop) you could make an image of a donut with a
transparent hole in the middle that another image can be seen through.
You could make an image of a new red Corvette sports car and through
the windshield see your great grandfather as the driver (takes some
skill and time!).
RAW is a digital camera file format that is not available in all
digital cameras. The various camera makers have not agreed on a common
term for the RAW file format so each camera makers may used a separate
term for this. A RAW digital file is, in essence, the exact pixel data
that the digital camera's engine captures. However, you can't display
RAW data on screen and it first has to be converted. Photoshop offers
some significant and serious options and settings for working with RAW
data files. A RAW photo image file can be very large. I've worked
with photogs who may often be using a single image file done via a RAW
camera setting that is 250 GB is size.
Nikon's term for RAW is NEF. I think Canon uses the term CR2 for RAW.
Sony uses the term ARW for RAW.
Many decent ink jet printers are optimized to do a nice print of JPEG
files because it's such a popular format but IMO anything below 300 dpi
results in loss of quality. However, there are so many factors
involved from quality of the printer, type of ink, color calibration
process used, quality of paper, settings for the printer, that it's
impossible to generalize on this topic.
As I mentioned in part above, I normally set my DSLR camera to the 300
dpi JPEG setting. If I know in advance that I'm taking pictures that I
will want to enlarge, or to edit extensively, or to print at high
quality on high quality ink jet paper, I set the camera to the RAW file
format. Before I will print a 300 dpi JPEG file, the first thing I do
is open and save it on the Mac as an Adobe Photoshop PSD file format
and edit in that. For images that I will send via email that won't be
printed, I'll edit the image and convert to 72 dpi JPEG.
Good luck!
Denver Dan
On Sat, 12 Jan 2013 14:50:52 -0800, Dave C wrote:
> "If a train leaves Chicago traveling west..."
>
> A color jpg file is 1.9 MB (Finder says: 1,940,805 bytes); image
> size: 1024 x 768.
>
> 1.9 MB divided by the image size gives something like 2.4, which is
> not 8 bits per pixel or such.
>
> Why can't I make the numbers agree? I know it must be something simple...
>
> Thanks,
> Dave
>
Dave, several responders have suggested that you are seeing the results
of the lossy JPEG file format.
Book Alert! A long reply follows. Only read if interested in the
topic of compressed and lossy file formats.
A JPEG image is a compressed file format. The JPEG compression is a
type that when the JPEG file is saved data is permanently discarded in
order to make the file smaller.
Most software programs, and digital cameras, can be set for different
levels of JPEG compression. Normally you can pick between JPEG levels
of 1 to 10. A JPEG level 1 is very high compression (and high loss of
data) up to a JPEG 10 with low compression (a bigger file) and low data
loss.
Video files, I think nearly all of them, are also compressed. Many
video compression methods are available and these use something called
a Codec (or, Compression/
other.
Music files are also often compressed. A very common audio file is the
MPG which is highly compressed (and lossy). If you look at the import
preferences for iTunes it gives you several different types of RIP file
formats for when you import/RIP an audio CD into iTunes and some are
lossy and some are not. The non lossy music file formats result in
larger music files but usually better audio.
A GIF image file format is also a compressed file format but different
from JPEG. While a JPEG file can contain millions of colors and GIF
file can only have a maximum of 256 colors so a good quality photo that
is saved in GIF format automatically losses all of those colors, hues,
shades. But a GIF file can also be saved with fewer colors. One
reason that GIF is still used is that a GIF file can have just one
color, or just two colors (like a black and white corporate logo) and
this results in a tiny file size that downloads very quickly on a web
page. A GIF file can also be used for other web page tricks such as
files with a transparent background color or an animated GIF file that
appears to be a short movie (it's really a series of images each of
which is slightly altered to mimic motion).
You may see the term CompuServeGIF (in Adobe Photoshop, for example)
because CompuServe originally developed the GIF file format back in the
days of SLOW dialup internet. A legal wrangle over GIF resulted and a
newer file format called PNG was developed. PNG can combine the
flexibility of JPEG and GIF and if used properly can result in small
but high quality compressed images but PNG hasn't really caught on in a
big way.
Professional photogs will shoot pictures in a high quality JPEG file
format but they understand that if they edit and save a JPEG multiple
times it will soon loss so much quality as to become unusable so before
editing they will convert the JPEG to a format like Photoshop'
lossy high quality format for editing. I keep my Nikon DSLR camera
set at the 300 dpi JPEG file format rather than a lower quality file
format because this works well for quality, for most smaller snap shot
paper sizes (like 4x6 inches) if I want to print, and it means more
images can fit on a hard drive or SD camera card. Of course, if I
picked a 72 dpi JPEG size a LOT more pictures could fit on the SD
camera card but 72 dpi while it will look just fine on screen is just
way too low a resolution for even medium quality printing.
TIFF is used as a good quality and non lossy file format for images for
photo graphics and desktop publishing. TIFF image file format was
initially developed for scanning of photos. Some digital cameras can
be set to make TIFF images. A TIFF image file retains aspects of the
original photograph&#
image. TIFF images can also be compressed but the technique is not a
lossy compression
ESP is another image format. Mostly used by professionals these days.
ESP, meaning Encapsulated PostScript, offers some fun tricks for those
who would like to work in programs like Adobe Photoshop to achieve some
nifty results on paper. An ESP can be any shape, can have transparent
parts, and other effects. For example, if you spend a few minutes in
Photoshop learning to create a clipping path (see Clipping Mask in
recent versions of Photoshop) you could make an image of a donut with a
transparent hole in the middle that another image can be seen through.
You could make an image of a new red Corvette sports car and through
the windshield see your great grandfather as the driver (takes some
skill and time!).
RAW is a digital camera file format that is not available in all
digital cameras. The various camera makers have not agreed on a common
term for the RAW file format so each camera makers may used a separate
term for this. A RAW digital file is, in essence, the exact pixel data
that the digital camera's engine captures. However, you can't display
RAW data on screen and it first has to be converted. Photoshop offers
some significant and serious options and settings for working with RAW
data files. A RAW photo image file can be very large. I've worked
with photogs who may often be using a single image file done via a RAW
camera setting that is 250 GB is size.
Nikon's term for RAW is NEF. I think Canon uses the term CR2 for RAW.
Sony uses the term ARW for RAW.
Many decent ink jet printers are optimized to do a nice print of JPEG
files because it's such a popular format but IMO anything below 300 dpi
results in loss of quality. However, there are so many factors
involved from quality of the printer, type of ink, color calibration
process used, quality of paper, settings for the printer, that it's
impossible to generalize on this topic.
As I mentioned in part above, I normally set my DSLR camera to the 300
dpi JPEG setting. If I know in advance that I'm taking pictures that I
will want to enlarge, or to edit extensively, or to print at high
quality on high quality ink jet paper, I set the camera to the RAW file
format. Before I will print a 300 dpi JPEG file, the first thing I do
is open and save it on the Mac as an Adobe Photoshop PSD file format
and edit in that. For images that I will send via email that won't be
printed, I'll edit the image and convert to 72 dpi JPEG.
Good luck!
Denver Dan
On Sat, 12 Jan 2013 14:50:52 -0800, Dave C wrote:
> "If a train leaves Chicago traveling west..."
>
> A color jpg file is 1.9 MB (Finder says: 1,940,805 bytes); image
> size: 1024 x 768.
>
> 1.9 MB divided by the image size gives something like 2.4, which is
> not 8 bits per pixel or such.
>
> Why can't I make the numbers agree? I know it must be something simple...
>
> Thanks,
> Dave
>
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