I have an Autocad drawing which is a plan for land squares where each square contains a number.
I tried to convert it to image by choosing: File --> Export Data --> and file format Bitmap (bmp). (I have Autocad 2013 Mac version)
the file converted to image, but the quality is too bad, I can't see the land numbers inside the square when I zoom in the image.
I tried also with Postscript (PS file format), quality is a bit better but it's still bad.
Is there away to convert Autocad file to image but still preserve it's high quality details
I need to convert the file to image because I would like to publish it online on my website. maybe there other was to publish autocad file on line, if so, please advice. But the trick I want the background of the autcad (plan) to be transparent so that I could display it on top of Google maps. I if I used autocad plugin I can't make it transparent. right?
Use the PLOT (for the current drawing) or PUBLISH (for batching) commands to produce high quality images.
Related
I noticed that PNG files created by Gimp from the same RPG data are identical except for the very beginning. This image shows a diff of otherwise identical PNG files created with Gimp:
What is this data which changes each time and how is it encoded? Are there tools to decode it? Can you learn something from this information, e.g. can you find out when a PNG file was (probably) created by this information?
I was under the impression that PNG files are created deterministically* and don't store meta data which isn't necessary to decode the image. (Obviously, the last part is not true, either, as Gimp writes its own name into the files but doesn't ask the user (which is does if you export something as a JPEG file).)
* I use the word "deterministic" here to refer to things and only such which are the same on each execution/export/whatever given the same input. I'd usually use the word "functional" (i.e. like a mathematical function) but I fear this could be misunderstood by people who don't know what "functional" means in mathematics. Obviously, this is different from the usage of this word in information theory.
See the PNG header definition.
tIME stores the time that the image was last changed, so for me it's the same as the timestamp of the file you create.
bKGD gives the default background color. Possibly the bakcgournd color you are using in Gimp, or the color of the transparent pixels.
tEXT with key Comment and value Created with Gimp is just the default comment. You can change the comment for the image in Image>Properties and you can set a default comment in Edit>Preferences>Default Image
When I export the same PNG twice, I only see a change in tIME. In fact I can't get a bKGD item, even when exporting a PNG with transparent pixels. Are you using any specific options when exporting?
I'm building a web application (RoR) that manages images that are in raw image format. I need to create thumbnail/web versions of these images to be displayed on the site. Currently, I'm using imagemagick, which delegates to dcraw to produce the jpeg thumbnail. The problem I'm running into is that the thumbnail deviates from the look of the original; the image gets darker and the white balance is sometimes heavily shifted.
I'm assuming that the raw format default setting can't be read by dcraw, and thus it's left guessing how to parameterize the raw conversion. I can play around with customizing these setting, but it seems getting it right on one image causes others to be further off the mark.
Is there a better way to do this in order to get a result that more closely mimics the what I might see in a raw viewer like photoshop, or even Mac OSX preview? Given that Mac OS X supports a variety of digital camera raw formats, is there anyway to utilize the OS's ability to render preview images (especially considering that result is what is expected).
The raw images that I'm using are 3FRs and fffs (both from Hasselblad).
I can post samples if people are interested.
Thanks
Look at "sips" and "Resizing images using the command line" to get you started.
I opened one PNG file in Inkscape and exported it as SVG. When I opened that file with notepad I came to know that the PNG file is embedded within it. If the conversion happened then the resulting file should have only SVG related tags. It shouldn't embed the image within it. Or Am I doing anything wrong.
Note: Save as option also producing the same kind of file. I am using Inkscape version 0.48 in Windows 7 - 64 bit.
This is a bit of an old thread, but it comes up early in Google so I thought I'd contribute something.
In Inkscape, you must do a trace to change the image into SVG. Look at the Path | Trace bitmap menu item and play with the options on that screen.
After creating the trace, you can remove your source image and have a pure svg in your saved file.
I've found it helpful to create layers in Inkscape and move the source image to one layer and put the trace on another layer to let me make quick comparisons using the 'hide layer' buttons.
BTW, your source image can be anything - bmp, jpg, png, etc.
A .png file is a raster image file. In order to convert it to a vector graphic based format like .svg and have it be "native" svg rather than an included image you are going to either have to use a program that can rasterize it or in Inkscape trace the bitmap and turn it into paths. Inkscape provides information on tracing: http://inkscape.org/doc/tracing/tutorial-tracing.html
I use Abbyy FineReader for ScanSnap to OCR a couple of scanned PDF files. The software claims it retains the original PDF images. The PDF file sizes pre-OCR and post-OCR are almost identical, which is good.
After the software is done, all PDF images appear anti-aliased in Acrobat X. Page navigation is much slower than before, and when I zoom in/out, the images first go to what looks like the pre-anti-aliasing version before quickly changing to anti-aliased images.
Left: Scanned PDF / Right: after OCR with Abbyy
I would like to get the original images without anti-aliasing back. Interestingly, when I open a single page from the anti-aliased PDF in Photoshop, there is no anti-aliasing and the image looks like the left one.
My limited PDF programming experience leads me to believe that Abbyy likely sets some kind of anti-alias flag for each image during OCR processing. How do I un-set this flag?
Any pointers to useful ideas would be much appreciated.
After the software is done, all PDF images appear anti-aliased in Acrobat X. Page navigation is much slower than before, and when I zoom in/out, the images first go to what looks like the pre-anti-aliasing version before quickly changing to anti-aliased images.
Actually in the original file 2013_11_15_22_51_31.pdf contains a JPEG image while the OCR'ed file 2013_11_15_22_51_31_OCR.pdf contains a JPEG2000 image.
Comparing them in third party viewers, it becomes clear that the image in the OCR'ed file is not inherently anti-alias'ed. Furthermore there is no evident flag in the PDF instructing PDF viewers to apply anti-aliasing to the JPEG2000 image. Thus, Adobe Reader seems to automatically render JPEG and JPEG2000 images differently, applying anti-aliasing to the latter but not to the former.
Comparing both images in detail, though, it becomes clear that these images are not identical but instead the image in the OCR'ed PDF is slightly rotated.
I assume Abbyy FineReader recognized that the original scanned image is not correctly oriented. Thus, it rotated it slightly to correct this orientation.
Thus, replacing the image in the OCR'ed version with the one from the original one is no option: Due to the rotation the OCR information would partially be somewhat off.
What you might want to try is to recode the JPEG2000 image to JPEG and replace the image in the OCR'ed version with this recoded one. This will mean some loss of quality but most likely you can get rid of the anti-aliasing this way.
Be aware, though, that the JPEG2000 image is slightly larger than the JPEG image to accomodate for the rotation.
PS: As #VadimR pointed out, there is indeed an /Interpolate true entry in the image dictionary of the OCR-ed version I missed when looking at the file. This does not seem to be the major issue slowing down the rendering.
There is /Interpolate true entry in image dictionary of OCR-ed version, and that's what causes 'anti-aliasing'. Whether that (and not JPEG2000 instead of JPEG compression) is a cause of slow-down, you check on large enough files.
To un-set this key, the best would be to turn it off while creating a file, and if that's not possible, to write and run a small program in suitable language.
But, since your file doesn't sport 'compressed objects' and offending key is in plain view inside a file, in the spirit of 'job done quickly' you can simply process your file e.g. like this:
perl -M-encoding -0777pe "s!/Interpolate true!' 'x17!ge" <in.pdf >out.pdf
Here is an image:
This image is a simple black-to-transparent gradient saved in full RGBA PNG.
Here is the same image, converted to indexed-alpha PNG by GIMP (Photoshop produces the same result)
As you can see, the gradient is now half-opaque, half-transparent.
Here is the same image again, only this time it was converted to indexed-alpha PNG by a PHP script I wrote:
So my question is: Why are GIMP and Photoshop unable to support partial transparency in indexed images, when the PHP script clearly shows that such an image can be created with no problems?
Is there anything "wrong" with an image whose pallette contains alpha information?
A more programming-related question: Does this transparency in the last image work in Internet Explorer 6?
I've finally found the actual answer: There is a metadata entry that allows you to define the alpha value of each colour in the colour table. Most graphics programs don't make use of this, but it does exist and can be used, in particular by GD.
Another option besides fireworks is pngquant, a command line application that will convert a rgba png into an indexed png with transparency.
I found this post which talks some more about how to use it.
IE6 and earlier in windows does not support variable transparency PNGs without annoying workarounds. An indexed PNG will only show the fully opaque parts which usually works pretty well. A drop shadow would disappear but the opaque parts of the logo or icon would continue to show.
This page has a better explanation and instructions with more png compression and quantization tools: http://calendar.perfplanet.com/2010/png-that-works/
For the record, PNG does not literally support indexed images with an alpha channel. What is really happening is that PNG allows you to add additional colors to the color table (i.e. index) with alpha values in those colors... not a complete alpha channel. FWIW...
Yeah I know what you mean. Fireworks is the only image editing program that I know of that can create and edit PNG8+Alpha without problems. I wish more paint programs would support this format cause Fireworks is expensive!
I found a way in GIMP to create or convert an image with reduced color palette and alpha channel.
The trick is to add a mask to the layer.
Full steps to reproduce:
Have your image in one layer
Add a mask to the layer. Select Transfer layer's alpha channel.
Convert to Indexed (Image -> Mode -> Indexed...)
Save as PNG
Now your image has reduced colors and reduced size, but it keeps your smooth transparency.