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#1
Beginner Talk / Re: Why use DPI (not ppi)? (im...
Last post by Yichuang驿窗 - June 22, 2024, 12:57:00 AM
A Dot is a Pixel, maybe YES, maybe NO.

Example for YES:
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An image file is 600x300 px,resolution is 300 PPI,it was printed on a paper with a laser printer, the accuracy of the laster printer is 300 DPI.


The printout result is,an image on paper that is 2 inches in horizontal dimension and that 2 inches consists of 600 pixels. The image is 1 inch in portrait dimension and the 1 inch consists of 300 pixels.

"2 inches in horizontal dimension" is because of 600px÷300PPI, "1 inches in portrait dimension" is because of 300px÷300PPI.

Because the printer's accuracy is 300 DPI, the printer will print 300 Dots on a one-inch length of paper. Corresponding to the image printed above, the image is 2x1 inches, so 600 Dots are printed horizontally(2 inches x 300 DPI); 300 Dots are printed vertically(1 inch x 300 DPI).

Summary:
An image on paper has 600 Pixels in the horizontal direction, and these 600 Pixels are rendered by the printer with 600 toner Dots; in the vertical direction, there are 300 Pixels, and these 300 Pixels are rendered by the printer with 300 toner Dots.

Here, the pixels and toner dots correspond to each other, and the result is what we call "A dot is a pixel".



Example for NO:
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Same image file, same laser printer. Before printing, we change the resolution of the image from 300 PPI to 600 PPI, then print the image to paper and see what changes.

(Note that the image file is now 600x300 pixels, the resolution is 600 PPI, and the printer precision is 300 DPI).

Since the image has a resolution of 600 PPI, the image printed to paper is 1 inch (600px÷600PPI) horizontally and 0.5 inches (300px÷600PPI) vertically.

While on paper, the printer still uses 300 toner dots to render an inch long image content, that is, 1x0.5-inch image, horizontal 1 inch, there are 300 toner dots; vertical 0.5 inches, there are 150 toner dots.

The result is that printing a 1x0.5-inch image on paper with 600 pixels an inch horizontally requires only 300 toner dots; printing a 0.5-inch image with 300 pixels vertically requires only 150 toner dots.

Summary:

An image on paper has 600 pixels in landscape, which are rendered by the printer with 300 toner dots, and 300 pixels in portrait, which are rendered by the printer with 150 toner dots.

Here, the pixels and toner dots are not one-to-one and become "One dot is (rendered with) Two pixel".


======================
In the above examples, if the precision of the printer changes(300DPI to 600DPI, or 300DPI to 150DPI), it will likewise affect the toner_dot-to-pixel correspondence.

So, exactly how the dots correspond to the pixels is mainly affected by two elements, one is the resolution PPI of the image and the other is the precision DPI of the printer.

However, the only element that determines the size of an image on paper is the PPI, not the DPI.
#2
PDF Generation / Re: Best pdf output for Family...
Last post by FemmesoleNZ - June 22, 2024, 12:17:57 AM
I have just tried this out; see results in image. Was much easier. The lower part is using the vector method you described and this seems to have changed the output such that the font now appears 'cramped' and much harder to read in my opinion, while the upper part is from importing the png. I think the vector method would be better, but I would have to experiment with fonts to find an appropriate one for the original file. I know it is not usual, but I found that the best font for getting a great deal of information on a page was Arial Narrow, so I have used only Arial Narrow and Arial Narrow Bold in the reports from Legacy, and thus elsewhere I have used text. The text is generally size 12; so reduces slightly when imported into the image frame in Scribus.

As I am halfway into the second book of a two part set, I am not going to change the method now, but I really appreciate your giving me this assistance and certainly something to experiment with. Thank you very much.

#3
Features / Re: Make gradients easier to m...
Last post by tim_occ - June 21, 2024, 11:37:54 PM
This is how it looks like in Scribus 1.7.0 svn.
#4
Beginner Talk / Re: Why use DPI (not ppi)? (im...
Last post by a.l.e - June 21, 2024, 04:28:27 PM
"""
In simple, rudimentary, terms...

  • A dot is the smallest possible spot of ink on paper.
  • A pixel is the smallest possible spot of light on a screen.

Dots are never on a screen and pixels are never on paper.
"""

https://graphicdesign.stackexchange.com/a/154690

this is the short version of the fine explanation by yi chuang.
#5
Beginner Talk / Re: Why use DPI (not ppi)? (im...
Last post by RodneyLee - June 21, 2024, 02:54:33 PM
A DOT is a PIXEL
#6
PDF Generation / Re: Best pdf output for Family...
Last post by a.l.e - June 21, 2024, 11:22:42 AM
for future reference (since you seem to have produced your book now): you might want to directly import the pdfs page by page as vector (without first selecting an image frame).

probably, you will want to import the text as vectors.

- make sure that your document is active and no frame is selected
- file > import > get vector file
- pick the pdf
- choose the page to be imported
- choose to import the text as vectors
- you will get the pdf as grouped vector drawing (it will not be in a frame and you can ungroup it; of course, you won't be able to modify the text)
#7
PDF Generation / Re: Best pdf output for Family...
Last post by FemmesoleNZ - June 21, 2024, 11:03:13 AM
Sorry did not attach file; now attached. Not sure how clear this will be.
#8
PDF Generation / Re: Best pdf output for Family...
Last post by FemmesoleNZ - June 21, 2024, 10:53:08 AM
Thank you both for your replies. Yes, I am well aware of the Preview Settings in Scribus and use them also as you describe. Do not compress when exporting pdfs from anywhere.

I export all the charts (usually single page) and the Family Group Reports (multipage) from Legacy to pdf files; convert so that each page is .png; set image frames in Scribus and "get image" for each page. For text I want to add, I use the Scribus Text Frames. Also add other images as required into 'white spaces', e.g. enlargement of grave image or probate entry.

I am not sure where the problem with the font conversion occurs, but its effect is significant. Attached find a sample I just made by importing part of a Family file as png into an image frame on the top of the page and a pdf version into an image frame at the bottom of the same page. The pdf import is not as clear as the png import, although this time it is not as bad as it was when I imported a whole file this way. Both preview settings at full resolution.

Certainly interesting; but thanks to Scribus that I can actually produce a reasonable book anyway!





#9
Beginner Talk / Re: Why use DPI (not ppi)? (im...
Last post by Yichuang驿窗 - June 20, 2024, 04:36:29 PM
I think it should be PPI, not DPI.

First look at the ppi.
The sole purpose of ppi is to determine the physical print size of a pixel. Assuming an image is 600x900 pixels, what is the size of that image when printed or printed to paper?

This is when ppi is used. if the resolution of an image is 300 ppi, that means 300 pixels spread over the length of an inch, then the physical print size of each pixel is 1/300 of an inch = 0.003 inches. a 600*900 pixel image with a resolution of 300 ppi translates to a print size of 0.003x600*0.003x900. That ends up being 2x3 inches.

No dpi is used in this process, only ppi.

Look at dpi.
dpi initially describes the performance of the printer, said the printer in the length of an inch of paper can print how many dots.

Let's say the resolution of a printer is 300 dpi, which means that this printer can print 300 dots on a length of one inch of paper.

Or, to describe a scanner, it means that the scanner can read information about how many dots on one inch from the paper. There is no ppi involved here, only dpi.

Now we have a look at Scribus.

In Scribus we need a ppi to tell printer how much the physical print size of the image pixel is. For this reason, we need only ppi, not dpi.


-------
DPI is for printer, like laser heads for laser printers, or printheads for inkjet printers. The dpi only reflects the level of accuracy of the printer itself and has nothing to do with the image.
#10
Beginner Talk / Re: Why use DPI (not ppi)? (im...
Last post by Aleks100 - June 20, 2024, 01:46:51 PM
DPI, for sure. Google dpi vs ppi