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Help Using Inkscape => Inkscape Beginners' Questions => Topic started by: Gecko on January 15, 2019, 02:11:58 AM

Title: Export As same Quality as Save As?
Post by: Gecko on January 15, 2019, 02:11:58 AM
Hey guys.

I created a vector image using trace bitmap.

Is the rendered image the same quality when I export the .svg to png via >File>Save As>.png and >File>Export PNG Image?

Title: Re: Export As same Quality as Save As?
Post by: brynn on January 15, 2019, 02:53:14 AM
If your goal is to end up with a PNG, then you can skip using Trace Bitmap to convert to vector.  PNG is a raster format.  You didn't say what your original is, but if you used Trace Bitmap, that would imply that it's some raster format (PNG, JPG, GIF, etc.)  Converting to vector and back again to raster will surely lose some quality.

What is the original format?

If you can share, what is your ultimate goal?  Maybe we can help you find the best route to reach your goal?
Title: Re: Export As same Quality as Save As?
Post by: Moini on January 15, 2019, 06:50:19 AM
Don't use File > Save as... > Cairo PNG. A Cairo PNG does not support all the features of a normal PNG, e.g. there is no transparency, and (I think) filters will be lost, too. Also, you cannot select a resolution.

Use the Export dialog, with all the options it offers.
Title: Re: Export As same Quality as Save As?
Post by: Gecko on January 15, 2019, 07:58:07 PM
If your goal is to end up with a PNG, then you can skip using Trace Bitmap to convert to vector.  PNG is a raster format.  You didn't say what your original is, but if you used Trace Bitmap, that would imply that it's some raster format (PNG, JPG, GIF, etc.)  Converting to vector and back again to raster will surely lose some quality.

What is the original format?

If you can share, what is your ultimate goal?  Maybe we can help you find the best route to reach your goal?

Thanks for the useful answers.

My goal is to vectorize my designs, upscale them in vector so it doesn't lose quality (ex. pixelate as in raster), and then back to .png with a bigger pixel size. So my original format at the moment is .jpg (my mobile camera format ) which when is processed with Gimp becomes .png. When I use Pro Motion NG is .png as well.

I'm doing this so I can send files (.png) to a online printing type company that sells your designs in t-shirts, stickers, spiral notebooks, mobile phone cases, etc, so I have to send them a big file in pixels - 7632x6480 - . And I want less quality loss or no quality loss.

At the moment I'm working on black and white, pen ball designs on white paper, mostly, but I will add different types of designs to my portafolio/online shop soon. But these which I'm working at the moment are hand drawings which I take photos - 23 megapixels camera resolution and 5520x4144 pixels - then I process them with Gimp, and then to vectorize and change it's size I use Inkscape, which I'm learning the process. I work sometimes in Pro Motion NG, and because that's a different type of software, sometimes the pixel dimension of the canvas has to be way smaller than desirable to create the pixelated effect, and that has to be made a bigger file size in pixels as well, without losing quality. I'm planning on learning to vectorize those too. Those are mostly in 8-bit, 16-bit, 32-bit and 64-bit scale color.

Any help or further approaches which I can take are greatly appreciated.
Title: Re: Export As same Quality as Save As?
Post by: brynn on January 17, 2019, 02:52:56 PM
That's an interesting, and clever approach!  Some of it is probably over my head.

You'll want to keep in mind that Trace Bitmap is not designed to precisely duplicate raster images in vector form.  Depending on how small the original image is, and also on the complexity and quality of the image, you could even see small descrepancies at 100% zoom.  The larger the original, the better.  And the less complex the original, the better.  Very thin lines might not display very well.  (I'm not sure if "pen ball designs" means ball point pens drawings???)

Yes (agreeing with Moini), File menu > Export PNG is the best option.  I don't think you will see any noticable difference between the vector version and the new PNG version.  However, as I mentioned, you might see some difference between the original raster and the new vector version.  If the originals are 5520x4144 pixels, you probably won't see much difference.....although if it's ball point pen drawing, I'm just not sure.

I guess you can only try it and see what happens though.

Just out of curiosity though, isn't 7632x6480 pixels way bigger than a tshirt, and any of the other products you mentioned?  It seems like the original size you mentioned (5520x4144) would be big enough?  (This is the part that's probably over my head.)  I just did a very quick and very rough calculation, and 7632x6480, at 96 dpi, is a little over 6 feet x 5 feet.
Title: Re: Export As same Quality as Save As?
Post by: Moini on January 17, 2019, 03:10:27 PM
Btw. Brynn, you'll be glad to learn that the Cairo PNG export has finally been removed from master (by Marc). The T-Shirt is probably *supposed* to be printed at a much higher dpi.Print shops sometimes don't adapt their requirements to material, so they might request 300 dpi or more.
Title: Re: Export As same Quality as Save As?
Post by: brynn on January 17, 2019, 04:37:47 PM
Btw. Brynn, you'll be glad to learn that the Cairo PNG export has finally been removed from master (by Marc). The T-Shirt is probably *supposed* to be printed at a much higher dpi.Print shops sometimes don't adapt their requirements to material, so they might request 300 dpi or more.

Thanks.  Yes, glad to be rid of cairo png!  Was just beginning to wonder if Inkscape really needed it.
Title: Re: Export As same Quality as Save As?
Post by: Gecko on January 17, 2019, 11:01:13 PM
That's an interesting, and clever approach!  Some of it is probably over my head.

You'll want to keep in mind that Trace Bitmap is not designed to precisely duplicate raster images in vector form.  Depending on how small the original image is, and also on the complexity and quality of the image, you could even see small descrepancies at 100% zoom.  The larger the original, the better.  And the less complex the original, the better.  Very thin lines might not display very well.  (I'm not sure if "pen ball designs" means ball point pens drawings???)

Yes (agreeing with Moini), File menu > Export PNG is the best option.  I don't think you will see any noticable difference between the vector version and the new PNG version.  However, as I mentioned, you might see some difference between the original raster and the new vector version.  If the originals are 5520x4144 pixels, you probably won't see much difference.....although if it's ball point pen drawing, I'm just not sure.

I guess you can only try it and see what happens though.

Just out of curiosity though, isn't 7632x6480 pixels way bigger than a tshirt, and any of the other products you mentioned?  It seems like the original size you mentioned (5520x4144) would be big enough?  (This is the part that's probably over my head.)  I just did a very quick and very rough calculation, and 7632x6480, at 96 dpi, is a little over 6 feet x 5 feet.

These designs when vectorized are almost the same as the png file. I do some processing in Gimp, and with the actual choices in trace bitmap  it's hard to tell it's been vectorized. These designs are all in black and white, and most lines are thickish after processed in Gimp.

Yes, it's ball point pens :). I'm using that pixel size because that way I just send one file for all products, and they downscale it at their offices for the required products. For example a bed Duvet it's very large, but a Spiral Notebook is a small image. Instead of sending two files I send one.
Title: Re: Export As same Quality as Save As?
Post by: phiscribe on January 18, 2019, 11:13:37 PM
Btw. Brynn, you'll be glad to learn that the Cairo PNG export has finally been removed from master (by Marc). The T-Shirt is probably *supposed* to be printed at a much higher dpi.Print shops sometimes don't adapt their requirements to material, so they might request 300 dpi or more.

Hurray!