Changing size of BMP export

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TarekFM
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Joined: Tue Nov 30, 2010 9:05 am

Changing size of BMP export

Postby TarekFM » Sat Dec 11, 2010 9:15 am

Ok, so I m making a little bit of progress w/ inkscape..

I made a logo which I then used the export as bmp feature with. Subsequently, I realised the image was too small for my needs...yet I realised it always saves at the same size.

There is another way to save as a .bmp under the file heading, however, the paramaters seem to be in 1000000s and i have no clue what to relate those numbers to.
Plus it seems to take eons rendering with that option.

Is there a way to change the default render?

thx,
Tarek:)

TarekFM
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Joined: Tue Nov 30, 2010 9:05 am

Re: Changing size of BMP export

Postby TarekFM » Sat Dec 11, 2010 9:48 am

ok, i have solved some of my problem.......second question..

i have a logo on a the default black page....i have zoomed in so the logo is taking up the whole screen and i want to render it that way.

since the background is not an object, i cannot select or cut it out and just render that part....can i use the available parameters in the export to bitmap feature to accomplish this?
Cheers,
Tarek

edit: so i m trying to edit the parameters under the selection heading in export to bmp.
it seems like u have to be a mathematician to do so...when u edit one the others change and i have no clue what they others(xo,y1 etc) relate to, esp w/ such lrge amounts...not very intuitive.

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druban
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Re: Changing size of BMP export

Postby druban » Sun Dec 12, 2010 2:29 am

You can select your logo and in the export bitmap dialog click on the selection button at the top instead of drawing or page. This will "render" only your selection and everything behind it, but not anything that falls outside the boundaries of your object.
Probably what you are looking for.
Your background can be changed in the document properties (file menu) dialog box, to opaque, transparent, different color, etc.
Your mind is what you think it is.

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brynn
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Re: Changing size of BMP export

Postby brynn » Sun Dec 12, 2010 7:54 am

Please correct me if I'm wrong. But I think if Tarek uses export selection, it will still export at 100%, which is apparently too small. To make it bigger, you just need to select it, and scale it larger.

You can't scale AND export at the same time, from the Export Bitmap dialog. I'm not clear what the x0, y1, etc stuff means either. But the buttons above that (Page, Drawing, Selection, Custom) have always done the job for me.

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druban
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Re: Changing size of BMP export

Postby druban » Sun Dec 12, 2010 2:04 pm

I may be misunderstanding the complexity of the issue here. If you have a vector object that you want to export as a bitmap, you can export bitmap i.e. pixel images of several different sizes from the same svg file open in Inkscape by invoking the export bitmap dialog and changing the dpi of your export, in the section where it says 'bitmap size', the width and height of the bitmap is updated and you can be quite precise in scaling the bitmap.
the only problem might be if you try to print this bitmap from another program afterwards without paying attention to the resolution, but there are many ways to set the dpi of a pixel image when printing, and this is something everyone working with graphics should be (or become) familiar with...


rect3105.png
a bitmap exported at 5dpi - you can barely see it...
rect3105.png (537 Bytes) Viewed 2757 times


rect31051.png
the same file exported at 100 dpi! (the 505 dpi export would have been dramatic but it was too large)
rect31051.png (31.4 KiB) Viewed 2757 times
Last edited by druban on Wed Jan 19, 2011 6:29 am, edited 2 times in total.
Your mind is what you think it is.

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brynn
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Re: Changing size of BMP export

Postby brynn » Sun Dec 12, 2010 2:31 pm

But changing the dpi (dots per inch, right?) is not the same as scaling, is it? I don't understand what the difference is. I thought dpi was a measure of image quality, rather than size? Do I need to visit Wikipedia, for a lesson? :lol:

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druban
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Re: Changing size of BMP export

Postby druban » Sun Dec 12, 2010 2:50 pm

What do you mean by scaling? see the two bitmaps I uploaded. One is 20 times larger than the other, in pure pixels. It is not the small bitmap being scaled to a larger size - that would result in an unreadable image. try it with one of your own svg files - export at two very different dpi and open the resulting png's in GIMP and inspect them.
Incidentally you can use the scale image dialog in GIMP to set and reset the printing resolution (dpi) without affecting the pixel dimensions. Because of this it's confusing to talk about the size of the image - are we talking pixels or inches? the same pixel dimensions can have many different inch dimensions .... but you probably know all this, sorry to ramble on.
Your mind is what you think it is.

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brynn
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Re: Changing size of BMP export

Postby brynn » Sun Dec 12, 2010 4:54 pm

Oh yes, yes, I know what happens when you scale a raster format image. I was suggesting scaling it in Inkscape (making it bigger), before exporting.

Incidentally you can use the scale image dialog in GIMP to set and reset the printing resolution (dpi) without affecting the pixel dimensions. Because of this it's confusing to talk about the size of the image - are we talking pixels or inches? the same pixel dimensions can have many different inch dimensions .... but you probably know all this, sorry to ramble on.

No, I didn't know that, and that's why I was asking. So if we have a 100 x 100 pixel image at 90 dpi, and we export at 270 dpi (3 times 90), it doesn't just pack more pixels into the same dimension (therby increasing the quality)? It becomes 3 times larger but still contains 10,000 pixels...doesn't that reduce the quality of the image by -3 times?

Yeah, I think I'll groove on over to Wiki Image

Thanks druban :D

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druban
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Re: Changing size of BMP export

Postby druban » Sat Jan 01, 2011 5:50 am

So if we have a 100 x 100 pixel image at 90 dpi, and we export at 270 dpi (3 times 90), it doesn't just pack more pixels into the same dimension (therby increasing the quality)? It becomes 3 times larger but still contains 10,000 pixels...doesn't that reduce the quality of the image by -3 times?


It's complicated! If you have a 100 x100 image at 90 dpi (we are talking raster, not vector, right? Although perhaps originating from Inkscape) and change the resolution in GIMP to 270 dpi nothing in the image will change, - i.e.the number of pixels and the pixel dimensions will stay the same - but the image will print as only 0.37 inches wide as opposed to printing at 1.11 inches formerly. In addition when importing into other apps, it may (or, for less savvy apps may not) display at one-third its former size relative to other objects.
For, instance, in Word or OpenOffice the resolution of the raster image decides how much of the page it occupies, and therefore what size it will print. On the other hand, GIMP will only show you actual pixel dimension images - 1:1 display is going to be large for high res and small for low res, even though it will save the res data. On the other hand Photoshop, if you have it, will show you actual size if you have your display set to anything but pixels...

Off topic:
BTW, I'm sorry my response was so long in coming. I must have just blinked at the wrong time and missed your post...
Your mind is what you think it is.


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