Auto Crop - how does it work?

[Peter2]

I have two questions, maybe regarding the same thing.

a) Auto-Crop:
I don't understand how it works. What is "Tolerance", what is "Background color"???

b) Croping of white space:
I will get a lot of TIF files (black / white; 400 DPI, CCITT G4 or LZW), made by CAD programs. The "papersize" will be very large (i.e. 80 x 350 cm), but the "inked area" (the real printed area) will be much smaller (A4 - A1). The rest of the picture will be an emtpy area (white space). How can I crop (trim) the TIF to the "inked area + x mm white space"? With auto-crop?

Best regards

Peter

[Peter2]

Nobody knows it?

Please give me a hint.

Thanks

Peter

[xnview]

Nobody knows it?

"Auto crop" try to remove a border with same color (+/- tolerance)

[Peter2]

Nobody knows it?

"Auto crop" try to remove a border with same color (+/- tolerance)

Thanks, but I am still confused:
Tolerance in pixel / inch / cm / color depth?
How it works with B/W-Tiff?

Peter

[xnview]

Nobody knows it?

"Auto crop" try to remove a border with same color (+/- tolerance)

Thanks, but I am still confused:
Tolerance in pixel / inch / cm / color depth?
How it works with B/W-Tiff?

Tolerance is in RGB color
On B&W, tolerance is not used

[Peter2]

Thanks, now I could make a testfile.

Question:
I took a tiff, B/W, 400 dpi, CCITT G4, 89 x 350cm, 129 kB, and cropped it (background black).
The result is a tiff, B/W, 400 dpi, CCITT G4, 89 x 235cm (correct cropping) , but 444 kB.
Why?

Suggestion:
The cropping uses exactly the last pixel. It would be nice to add a "space-tolerance" (positive or negative value; absolute in pixel or cm or relative in %) that is added to the "last pixel". With "positive space" I can add a small white paperspace around the tiff, with "negative space I can crop i.e. a frame, draawn around the picture (I use plans which have a drawn border-line around the plan.)

Best regards

Peter

[xnview]

Thanks, now I could make a testfile.

Question:
I took a tiff, B/W, 400 dpi, CCITT G4, 89 x 350cm, 129 kB, and cropped it (background black).
The result is a tiff, B/W, 400 dpi, CCITT G4, 89 x 235cm (correct cropping) , but 444 kB.
Why?

Plase check the compression in option/Write

Suggestion:
The cropping uses exactly the last pixel. It would be nice to add a "space-tolerance" (positive or negative value; absolute in pixel or cm or relative in %) that is added to the "last pixel". With "positive space" I can add a small white paperspace around the tiff, with "negative space I can crop i.e. a frame, draawn around the picture (I use plans which have a drawn border-line around the plan.)

Ok

[Peter2]

Plase check the compression in option/Write

I have
"Colour: LZW"
"Black/White: CCITT G4"

"Only one strip" is not marked. If I mark it, I get immediatly the error "Not enough memory."

Peter

[xnview]

Plase check the compression in option/Write

I have
"Colour: LZW"
"Black/White: CCITT G4"

And which compression is used by the original?

[Peter2]

Can I send you an example?

Peter

[xnview]

Can I send you an example?

Peter

Yes

[Peter2]

I sent it now by mail.

Peter

[Peter2]

Hello Pierre

did you get the file (per hotmail)?

Peter

[xnview]

Hello Pierre

did you get the file (per hotmail)?

Peter

Yes, i'll reply asap

[Peter2]

It is clear now: due to more tags, written by Xnview (and not written by the other software), the file size increased.

Peter

(Thanks to Pierre.)