Still learning about DPI.

I'm uploading .png (exported from Inkscape .svg) into Bookemon. Bookemon's recommend to get the best quality printed book? - make sure photos/scanned images have resolutions between 200 to 300 dpi. I exported from Inkscape at 90 dpi thinking that would be ok, however the images I've uploaded into Bookemon have turned out with really bad quality, blurry, colour loss, not good at all. However quality is absolutely spot on, clear and bright prior to uploading to Bookemon.

200-300dpi seems huge and I did post a query in the Forum earlier about what dpi to use when exporting for large classroom screens. 90 was the recommend. So i must have figured that was good for everything.

So now I'm confused - I lack enough info to make sense of things.

What does exporting at 200-300 dpi offer in the finished product that 90 dpi doesn't? Why would Bookemon want 200-300dpi?

And exporting my smallest file (less detailed page of the book) at 280dpi is giving me a width of 12295 x height 9057 - and Inkscape is stuck unable to process it.

Apparently, you`ll need to walk trough...

DPI
Image resolution
Graphic display resolutions
Display resolution

If you do, hope you`ll understand why it`s difficult to answer your question in a few lines. For starters, it would be better if you start with a New Document set to 300dpi, rather than exporting the existing one with modified dpi`s.

" For starters, it would be better if you start with a New Document set to 300dpi, rather than exporting the existing one with modified dpi`s."

I have gone back into the original doc, into File / Inkscape Preferences and changed Bitmaps to 300 dpi.
In Bitmaps Oversample bitmaps is set at 2x2. (Whatever that means)
Bitmap editor is set at gimp.

And I'm awaiting the results!

...

Not good! Inkscape keeps crashing. Says it's encountered an error part way thru exporting. Have had 3 attempts, all failed.

Now reading up on Gimp and on trying to correct things thru there - I can see mention often being made (while googling for solutions) about being able to remedy dpi fpr printing purposes in Gimp, but, as yet I've found no step-by-step instructions or guides on exactly what to do. And having no knowledge at all means a step-by-step is must for me, lol!

"What are the actual dimensions of the drawing? Width and height (in inches)? 12,295 x 9,057 @ 280dpi amounts to a drawing that is roughly 44 in. x 32 in. Is Bokemon going to print it *that* big?"

I've resized the actual image to 9.701 inches H x 13.170 inches W.

"That setting is only applicable if you create embedded bitmap copies of an object from within Inkscape..."

Sorry 'bout this - being new to all this I don't know what 'embedded bitmap copies of an object' are.
If it means have I created pics outside of the final collection point - yes. Various items were all created in their own Inkscape files and then copy-pasted into the final file for composition. Am I on the right track as to what 'embedded bitmap copies of an object' are?

Perhaps, if you consult the chart (for which I gave you the link on a previous topic) you`ll see recommended dpi`s for a different occasions. But, if you have a couple of images with different dpi`s - it would be like having different occasions on a same place and at the same time ,)

Large billboards are printed with around 20dpi`s which means there`s only 20 "colored" dots per square inch. On the other hand, framed photo on your desktop or wall should have 300dpi`s. So, imagine viewing those two from a same distance - could be hard to get the right/whole picture, right? ,) Is there a reason not to dive a bit deeper in all of this stuff, since you plan to deal with it?

Inkscape gives you vector images, which you may scale to fit your preferences without any loss of quality, but if you need bitmaps/raster graphics included - you`ll need to know how. Ready for some scuba diving? ,)

Hi Maestral, reading my way thru, home too late and too tired to focus tonight so tomorrow night is the next 'study night'. Thanks for the links!

Also, please don't confuse dpi of display vs printing dpi's. You may want to search this forum because this issue gets talked about fairly often). I mention this because normally when people talk about 300 dpi - that's intended for printing, not viewing (and dpi printing is typically handled by the rendering menu on your printer). Changing the DPI # in the export in Inkscape only changes the size, not the quality. I'm also wondering after you exported your design at 90 dpi (which really means it exported at 100% size), and bringing it up as a png (into Bookemon? sorry, never dealt with Bookemon, don't even know what it is/does) - did you do a save as to another extension, like jpg, gif, etc? I ask, because when I bring up the exported png into GIMP and then save it as a jpg, there's a slider scale which let's me choose the quality - and I am wondering if you have that choice in Bookemon, so you can look for it.
I hope this didn't confuse you more, it's a lot to sort out.... and there are people who can explain it a lot better/clearer than I can. I just happen to sell to Microstock sites and it also takes a high quality file, and I have good quality outputs with GIMP.
good luck!

Don't feel bad. DPI is very confusing!

What do we have here, let's see:
When exporting from inkscape, you can set a "theoretical" resolution.
That only affects the picture's pixel dimensions.
More precisely, your exported png won't have the desired resolution, it will have the same resolution -90 dpi?- no matter what you set, just the image's size will change.
It will be counted as how the pixel dimensions should be set based on the original svg.

Thus both is correct. Partly.
When opened the png in like photoshop, you can change the resolution of the file, which won't affect the pixel dimensions.
Making it possible, to achieve a png with exactly 300 dpi resolution.
Thus, the bigger the exporting dpi you set, the higher resolution image you can make out of it, when printed in a size that has the dimensions set in metrics/inches.

On small images, like avatars, anti-aliasing is the main focus of quality.
That is displayed on screens, which all have different resolutions.
For an example a screen that displays 1366 pixels on 13,5 inches have a resolution of 101,185 dpi.
You can set some other displaying dimensions, but you will hardly get your screen displaying the images at their set dpi resolutions.
Which means, your 48/50 pixel sized avatar won't look any better if a bigger/bigger resolution image is used instead. (Only you could zoom in better, if ever such would be possible.)
Details lost by blurring is because anti-aliasing. If you export a bigger image and scale it down in gimp, the result might be better, but that's just because of the rendering method of inkscape's export could be improved.

Also, on the original post:
The print quality is not just based on the file you print.
If you don't use the right material, you can have a 1200 dpi png printed, that will look as a 200 dpi print.
To my knowledge normal text is quite legible when printed at 300 dpi, while photographs are better to be printed at least at 600 dpi.
The limit is a bit more: you can print even 1200/2400 dpi prints if you wish, but that's unlikely for printing books.

brynn wrote:Don't feel bad. DPI is very confusing!

It gets a bit less confusing if you stop thinking about it as a property of the image, and think of it as a property of the output device.

A monitor has a fixed DPI which varies from model to model. It's literally the number of pixels (dots) in a line of one inch. Inkscape assumes 90dpi as a reasonable approximation across lots of models, but unless your monitor is actually 90dpi this will be out. For example if I hold a physical ruler up to the screen on my two monitors a 100mm line at 1:1 zoom is actually drawn as 86mm on one screen and 93mm on the other. Inkscape Prefs > Interface > Zoom Correction Factor can adjust for this, but only for a single monitor.

If you use another output device, it will have its own native DPI. Typically a desktop printer will lay down ink at 300dpi. If you're not printing directly from Inkscape, but rather are rendering a PNG to put into another program or to send to another person or company, you'll need to know what DPI they will be printing at, and export accordingly. So if you know they print at 300dpi you just have to export at 300dpi (assuming the image is printed 1:1 and not scaled in some way).

That should be all there is to it, in theory. Your image has a certain number of pixels, and if output at 1:1 then the size will depend on the DPI of the output device. A 900 pixel wide image will display as 10" wide on a 90dpi monitor, but print at 3" wide on a 300dpi printer.



However there's a small spanner that can appear in this: Photoshop, and some other software, has a tendency to embed a dpi setting into an image. It should be a hint - a way to say to the printer "yes, I know this image is only 900 pixels wide, but if I tell you it's 90dpi you can scale it up so that it's still 10" even on your 300dpi printer". In practice this hint is often misunderstood by printing bureaus as a firm instruction, so they'll reject images that don't have the right dpi setting embedded into the image. In reality it's quite meaningless, as it doesn't change the number of pixels in the image, but that's why you often see people saying "my printer wants a 300dpi image, and says that the one I sent him is wrong" - it just means that the printer opened it in Photoshop, saw a figure other than 300dpi in the box, and decided to stop thinking at that point.

Getting a grasp of this now! And with answers come questions, lol! Should I be creating the pics in the first place at 300dpi; is it possible to alter Inkscape to initialize them at 300dpi? I think my understanding is that that's not possible, that Inkscape auto-sets everything right from the word go at 90dpi, which is unalterable ???

All taking a while to sink in.


The drawings I'm creating will be used two-fold.

1 - on a large classroom screen. (Opened online from a book publishing site)

2 - in printed form when uploaded to the publishing site. (The site requires 200 - 300 dpi for printing purposes)

However the same location/source will be used to both view the books online and to print the books from, meaning the printing company will print from the very same .png I upload into the online book-reader.

So having no background knowledge plus trying to resolve all that is turning me grey!

Eyesintheskies wrote:The drawings I'm creating will be used two-fold.
1 - on a large classroom screen. (Opened online from a book publishing site)
2 - in printed form when uploaded to the publishing site. (The site requires 200 - 300 dpi for printing purposes)
However the same location/source will be used to both view the books online and to print the books from, meaning the printing company will print from the very same .png I upload into the online book-reader.

You have some of the very best advice above from the most knowledgeable users on the forum.
To sum it up: you want PNG export. You know the printed size will be

... 9.701 inches H x 13.170 inches W

Is that correct? This is the size it will appear on the page? If so, as PT has calculated, the PNG exported from Inkscape needs to be about 1940-2910H x 2634-3951W in pixels. These numbers are low enough that you might as well target the high end of the range. Don't worry about anything else, just get the height and width fields of your export bitmap dialog to show these numbers. (If you have drawn it exactly to scale, fine, it will be probably be 300 dpi in the resolution box, but as Xav pointed out you can't assume that an inch on your screen at 100% means an inch anywhere else. So you could just as easily have worked at a different size - the only thing that matters is the H & W in the export box. Number of pixels is a constant - 100 px on my system is 100 pixels on your system. in the next step we will lock the print size down precisely.)

Once it has been exported you must open it in another program that explicitly allows you to set resolution independently of pixel dimension. The GIMP is one, I also use Faststone because it opens so much faster than GIMP. In either case you will want to open the image size/rescale/resize/whatever dialog box and adjust the print size to be what you want and watch the resolution change, or vice versa: change the resolution field to 300, but make sure the print size is what you want! This operation should not change the pixel dimensions of the image which in most cases is in the top half of the dialog, with print size and resolution in the bottom half.
Also you should not worry about the projection size. Most classroom projection displays will vary between 720 and 1200 pixels wide max. The scaling should be handled by the application running the display, so your only concern is to be more than the high end which you will be, by a lot. you also have to trust that the online reader will observe the embedded resolution. That's really out of your hands if you have to use the same file for everything. They'll probably convert PNG to JPEG anyway when they make the e-reader file.

Eyesintheskies wrote:Success! I now have the Inkscape image exporting as a .png with all info appearing in the export. I achieved this by altering the file size from roughly original size @ 3962 x 2911 to 1357 x 1042, and then exporting.

You posted this in a different topic. I assume it is the same file, though. Although I can see you are happy about it, this is one of those instances when one has to speak up and say that this will probably not work out well. Now your print resolution has dropped to 140. That's about the top resolution of good modern newspapers but not nearly good enough for books. In addition you really need to look at it in a program that clearly states the printing dimension and resolution or you might be in for a surprise! Sorry to harsh your wave!

I am obviously restating what has already been said above but I am making myself look smart by summarizing it. ... shoulders of giants, etc. Did it work?

Hi Druban, yes, I'm thinking things are not good, sigh! I've uploaded and taken the book to the publishing stage, it's now appearing online, but instead of it being sharp and crisp as it was when I created each page it's an absolute unreadable smeared blur. However, when I went into 'book proof' prior to publishing, which is meant to be as close to the finished product as possible, things looked clear and fantastic. I'm not sure if the problem lays at my end or if the online book store I'm using has put blurry quality stuff up to stop people from illegally using the content. Very disappointing result.


Time Lapse...

I dragged a .png page of my book exported from Inkscape at 90dpi into GIMP 2, used Image / Scale Image, set X resolution and Y resolution at 260 pixels /inch, saved, exported as a .png, uploaded and published to the online book site, and lo and behold the page was still a blurred unusable mess, even though the 'book proof' pdf on the site showed me a crystal clear page of my work. Somehow between 'book proof' and 'publishing' things are totally screwing up. Waiting to see what the online book co have to say after already telling me 'book proof' and the finished item will look the same. They most certainly do not.

Persistence is everything! Still persisting. (Getting old and grey in the process tho!)

You are probably on the right track about the security business. Try to zoom in on the PDF and check for sharpness. If it is still sharp at say, 300% zoom then things are (probably) fine. 'Many a slip between the cup and the lip' is the motto of print shops everywhere.

Hi Druban, yes, sharp as a whip at 300% in book proof. Book proof occurs prior to publishing.

However, the moment the work becomes 'published' it's another story all together. Even the pdfs post-publishing turn out dreadful: unreadable, so fuzzy and blurred they're bin-jobs. And reading online in the 'READ' mode is impossible, not one word is legible and my illustrations look just awful instead of glossy and sharp and rich with colour.

Which means the book cannot be viewed online (unless I want people to view blurred unreadable fuzz and of course form very negative opinions about my work, lol!)

However that's just one of these online book publishing stores. I may have to move on and test some others.

Meanwhile I'm still waiting for a reply from the book co, I have attached a copy of one page showing the fuzz and distortion so when I get a reply I'll post the guts of it so that anyone else going through my process can have a point of reference...

Pdf jpeg compresses every rasters embedded by default, you cannot get rid of that except avoiding the use of the raster elements.
Thus saving the svg straight to pdf is a better solution, than exporting to bitmap, and creating pdf-s out of the png-s.

Hi Lazur URH, head is spinning right now, lol!

I have the original Inkscape .svg in front of me now - not sure how to save the .svg straight to pdf, or how to then export the pdf to bitmap, or how to create a pdf out of the resultant .png.

Off for some researching now on all that and of course any advice on the steps to take is hugely madly welcomed!

There is an option to save as, where you can select the .pdf as a target format.
Then a panel will appear where you can set if the fonts will turned to be paths, what the rasterization dpi of the raster based filters will be, and alike.
Wasn't sure if the final format you needed was pdf and not a simple raster image, but that one I replied made me think of it.

Pdf can have raster based elements and vector elements too.
You can create pdf-s from straight rasters with pdf printers, like bullzip or cutepdf.
I have not much experience with them. Some of such pdf makers can have a setting for the compression ratio better then the other.

But why to export to rasters, when your original drawing is in vector format, and you want a simple pdf file?
It is much better for printing purposes.

Having these said, I'm guessing the next thing you will have to deal with is the cmyk colour mode, which yet I couldn't get right through inkscape, but there are some topics on this forum.
With making your print-ready files into cmyk, you can be sure that the print will be showing exactly the colours of your choice.

"But why to export to rasters, when your original drawing is in vector format, and you want a simple pdf file?"

I can't upload pdfs to the online book co. Only JPG, JPEG, GIF and PNG.

Still waiting on the co to reply about why the quality in their READ online after publishing is so poor. Hanging out for some direction from them on what to do... Trying all I can meanwhile.

Confusion is growing! Aaaahhhhh!

Trying to import an Inkscape .svg into GIMP.

I went to the GIMP help page and looked under 'I' in the index to find out how to import a file, however import wasn't listed.

Drag and dropping my Inkscape .svg into GIMP failed.

I checked on You Tube for tutorials on how to import but had no luck either.

Went thru every tab in GIMP and found nothing on import.

I can however drag and drop pngs etc in.

But I don't know how to import existing Inkscape svgs into GIMP.

Advice extremely welcomed.

From Bookemon`s Help page:
"I have designed my book on my desktop computer. My program allows me to save my book as PDF or as a Word document. Which document type would be better to use to make a book at Bookemon?
Unless you know how to output PDF files at a DPI settings greater than 150, we recommend that you output your work to Word (compatible with Word version Word 98 through Word 2007)."

It was elaborated so many times on this forum, and it appears that there are a few ways to deal with preparing and printing Inkscape files. If you try that Search box, at the upper right corner of the forum page - you`ll find out more about these ways. Still, aside of Lazur URH`s suggested pdf printers (with which I`m not familiar either) you could give it a try to Scribus, which appears to be one of the most reliable solutions in similar cases.

Also, you could export .png from Inkscape (following suggestions already given in this topic) and then open it in GIMP, while previously setting that New file in GIMP to 300 dpi`s.

"Also, you could export .png from Inkscape (following suggestions already given in this topic) and then open it in GIMP, while previously setting that New file in GIMP to 300 dpi`s."

I gave that a go however the online read quality in Bookemon was still terrible - however this might be caused at their end by displaying in low quality perhaps to prevent people from copying the work ???

Still waiting on that reply from them to help narrow down the cause of the low read-online quality.

Everything happens at the same time.
A very similar question at gimpforums about exporting a .svg to a raster format (png) at a suitable dpi for inclusion in a book. And here am I advising, not to use Gimp but to use Inkscape and here you are looking at the reverse.

To open a svg in Gimp is the same as any other supported image type. Gimp menu File -> Open
If you have to 'drag-n-drop' there is a small area above the tools for this purpose.

Then it becomes a little different from raster files, the default is a scaling value of 1 and a dpi of 90, very similar to exporting in Inkscape. To import at a larger size in Gimp, 3 settings have to be changed manually, the X & Y scaling values and the dpi.

looks like this: http://i.imgur.com/yTc8kwz.jpg

and a warning - Gimp can take a while to import if not using the default setting, so be patient, it has not stalled.

The next thing is before you export as a raster image, png, jpg, tiff, you have to set the print size;
Gimp menu Image -> Print size Default value is 72 dpi and for the above example would need upping this to 300.

All that is why I recommended the poster to use Inkscape.