PainShop Pro 9 - Lossless rotation - not working for some pix

Author

Lossless rotation - not working for some pix

Orrie

2007-07-18, 6:20 pm

Hi,

I just scanned some old photos using PSP 7 (my scanner is attached to an old
computer), saved as .PSP files and as sTIF's. I copied them onto a CD-RW and
transferred them into my main computer where I work with PSP 9.

I want to use "Lossless Rotation" in Browse, but the options (90 degrees
clockwise/counter clockwise, etc.) are grayed out, so I can't rotate the
pictures. This is true only of these few pictures; lossless rotation works
for other photos I scanned previously using the same process.

In the past I have scanned at 100s of photos the same way, and did a
lossless rotation on many of them.

What could be preventing me from rotating these?

Also, why is "lossless rotation" only avaiable in the Browser and not when
working with the individual image?

Thank you.

Orrie

Trev

2007-07-18, 6:20 pm

"Orrie" <EB3551@yahoo.com> wrote in message news:469d19d8$1_3@cnews...
>
> Hi,
>
> I just scanned some old photos using PSP 7 (my scanner is attached to an
> old computer), saved as .PSP files and as sTIF's. I copied them onto a
> CD-RW and transferred them into my main computer where I work with PSP 9.
>
> I want to use "Lossless Rotation" in Browse, but the options (90 degrees
> clockwise/counter clockwise, etc.) are grayed out, so I can't rotate the
> pictures. This is true only of these few pictures; lossless rotation works
> for other photos I scanned previously using the same process.
>
> In the past I have scanned at 100s of photos the same way, and did a
> lossless rotation on many of them.
>
> What could be preventing me from rotating these?
>
> Also, why is "lossless rotation" only avaiable in the Browser and not when
> working with the individual image?
>
> Thank you.
>
> Orrie
Lossless rotation is done without opening and thus decompressing the image.
Its just a remapping of pixel locations.
Once decompressed and rotated it would need recompressing that's the point
it looses more detail.

Lossless rotation is for jpegs as there the ones that are losey, You mention
PSPimages and tiffs Unless you converted to jpeg then you have nothing to
lose.

Spandex Rutabaga

2007-07-18, 6:20 pm

Orrie wrote:
>
> Hi,
>
> I just scanned some old photos using PSP 7 (my scanner is attached to an old
> computer), saved as .PSP files and as sTIF's. I copied them onto a CD-RW and
> transferred them into my main computer where I work with PSP 9.
>
> I want to use "Lossless Rotation" in Browse, but the options (90 degrees
> clockwise/counter clockwise, etc.) are grayed out, so I can't rotate the
> pictures. This is true only of these few pictures; lossless rotation works
> for other photos I scanned previously using the same process.

Lossless rotation is only relevant for images compressed with
lossy compression, namely those in the JPEG format. If you
were to open such an image, it would first be decompressed,
then you would rotate it, and finally you would compress the
image again to re-save it. This second compression would cause
some loss of image data because JPEG compression always
discards some image date, which is the way JPEG files end up
so small. Lossless compression is a way of rotating the file
contents in 90 degree steps without ever decompressing the
compressed image data. (There is simply some swapping around
of image coordinates.) This means there is no lossy recompression
so that the rotation ends up being lossless. With other file
formats that do not discard data when compressing (e.g. the
PspImage, TIFF and PNG formats among others) there is no need
to offer such an option since opening the file, rotating it
and re-saving in one of these formats causes no loss.

> In the past I have scanned at 100s of photos the same way, and did a
> lossless rotation on many of them.
>
> What could be preventing me from rotating these?

The fact that you aren't working with JPEG format images.

> Also, why is "lossless rotation" only avaiable in the Browser and not when
> working with the individual image?

When you open an image and rotate it in steps of 90 degrees (i.e.
you rotate it 90, 180 or 270 degrees) there is never any loss of,
or change in, the image data. This is because unlike rotation
at other angles there is no need to interpolate new pixel values
from the old. (Interpolate means make up values by doing some
math on the original values.) Instead, everything is done simply
by exchanging and/or inverting horizontal and vertical pixel
coordinates. The only reason any loss would arise in 90 degree
rotations is in re-saving the file in a lossy format. Consequently
the lossless rotation option is only offered for JPEG images so
you can avoid opening, decompressing and recompressing them.

Orrie

2007-07-18, 6:20 pm

Thank you Trev and Spandex.

As always, your explanations were clear and helpful. I had one of those "Of
course!" moments when I read your replies. Yup, PSP's and TIF's are
lossless! That's why I use those format when I scan in the first place! Duh!

Thanks for the lesson.

Orrie

"Spandex Rutabaga" <SpRu@agabatur.xednaps> wrote in message
news:469E7085.D33CD919@agabatur.xednaps...
>
> Orrie wrote:
>
> Lossless rotation is only relevant for images compressed with
> lossy compression, namely those in the JPEG format. If you
> were to open such an image, it would first be decompressed,
> then you would rotate it, and finally you would compress the
> image again to re-save it. This second compression would cause
> some loss of image data because JPEG compression always
> discards some image date, which is the way JPEG files end up
> so small. Lossless compression is a way of rotating the file
> contents in 90 degree steps without ever decompressing the
> compressed image data. (There is simply some swapping around
> of image coordinates.) This means there is no lossy recompression
> so that the rotation ends up being lossless. With other file
> formats that do not discard data when compressing (e.g. the
> PspImage, TIFF and PNG formats among others) there is no need
> to offer such an option since opening the file, rotating it
> and re-saving in one of these formats causes no loss.
>
>
> The fact that you aren't working with JPEG format images.
>
>
> When you open an image and rotate it in steps of 90 degrees (i.e.
> you rotate it 90, 180 or 270 degrees) there is never any loss of,
> or change in, the image data. This is because unlike rotation
> at other angles there is no need to interpolate new pixel values
> from the old. (Interpolate means make up values by doing some
> math on the original values.) Instead, everything is done simply
> by exchanging and/or inverting horizontal and vertical pixel
> coordinates. The only reason any loss would arise in 90 degree
> rotations is in re-saving the file in a lossy format. Consequently
> the lossless rotation option is only offered for JPEG images so
> you can avoid opening, decompressing and recompressing them.
>
>