Re: Bad rendering of PNG saved from GIMP
Gifs have binary transparency - a pixel is either 100% transparent or not at all. PNGs have 8bit transparency - 256 degrees of transparency To make transparency available to an image: right-click-Layers-Add Alpha Channel //if the option is greyed out, it's probably available already To paint transparent use the eraser tool and turn the "Hard Edge" option on. To make selections transparent: in the properties dialog:turn off the "Antialiasing" option for the tool your using then delete the selected area in any normal way if you're paranoid you could save your image as a gif and then open the gif and save that as a png...if you're paranoid If you're trying to enforce binary transparency on an existing image: mail me an example of what you're trying - or If the above doesn't solve your problem... sometimes it's nice to overkill... Sort your life out with http://www.TUTTiCOM.com
Re: Bad rendering of PNG saved from GIMP
Thanks muchly for the verbose explanation and tutoring! I'll let you know if I run into any problems, but I've got to give it a go myself. Thanks again. Too cool. ciaran o riordan wrote: Gifs have binary transparency - a pixel is either 100% transparent or not at all. PNGs have 8bit transparency - 256 degrees of transparency To make transparency available to an image: right-click-Layers-Add Alpha Channel //if the option is greyed out, it's probably available already To paint transparent use the eraser tool and turn the "Hard Edge" option on. To make selections transparent: in the properties dialog:turn off the "Antialiasing" option for the tool your using then delete the selected area in any normal way if you're paranoid you could save your image as a gif and then open the gif and save that as a png...if you're paranoid If you're trying to enforce binary transparency on an existing image: mail me an example of what you're trying - or If the above doesn't solve your problem... sometimes it's nice to overkill... Sort your life out with http://www.TUTTiCOM.com -- Until later: Geoffrey [EMAIL PROTECTED] Microsoft != Innovation
Re: Bad rendering of PNG saved from GIMP
On Tue, Aug 01, 2000 at 01:56:15PM +0200, Tom Mraz [EMAIL PROTECTED] wrote: maybe I make some mistake, but when I try to make PNG picture to use it on my webpage, when I use some color for background of the image and the same The on ly difference I can see is that you are using a pattern for the png background which is of course different. This is expected when you dither the image, so best do not convert your image to indexed format. -- -==- | ==-- _ | ---==---(_)__ __ __ Marc Lehmann +-- --==---/ / _ \/ // /\ \/ / [EMAIL PROTECTED] |e| -=/_/_//_/\_,_/ /_/\_\ XX11-RIPE --+ The choice of a GNU generation | |
Re: Bad rendering of PNG saved from GIMP
On Tue, Aug 01, 2000 at 01:56:15PM +0200, Tom Mraz [EMAIL PROTECTED] wrote: maybe I make some mistake, but when I try to make PNG picture to use it on my webpage, when I use some color for background of the image and the same The on ly difference I can see is that you are using a pattern for the png background which is of course different. This is expected when you dither the image, so best do not convert your image to indexed format. It's not problem of the indexed image. When you load the image into GIMP it is correct and the background color value is #f7e4ca as it should be and there is no dithering pattern. The dithering happens only on edges of fonts or so and there it doesn't matter. The algorithm of the used dithering first finds big surfaces of unique color and puts the color directly into palette. As to bad support of png in browsers - I thought that MSIE 5.0 and latest Mozilla nightly should be correct, or not? Tomas Mraz
Re : Bad rendering of PNG saved from GIMP
-- De : Marc Lehmann [EMAIL PROTECTED] À : Tom Mraz [EMAIL PROTECTED] Cc : [EMAIL PROTECTED] Objet : Re: Bad rendering of PNG saved from GIMP Date : Mar 1 aoû 2000 13:10 On Tue, Aug 01, 2000 at 01:56:15PM +0200, Tom Mraz [EMAIL PROTECTED] wrote: maybe I make some mistake, but when I try to make PNG picture to use it on my webpage, when I use some color for background of the image and the same The on ly difference I can see is that you are using a pattern for the png background which is of course different. This is expected when you dither the image, so best do not convert your image to indexed format. You can have 65K colour browsing operating various perturbations as well ... AFAIK PNG don't include transparent parameter ; GIF ought to be the best way to do that ... Regards, Fabian
Re: Re : Bad rendering of PNG saved from GIMP
Why ? GIF are commonly used for small pictures coz they give you 256 _real_ color palette ability The size is small . what's the problem with GIF ? OK, maybe I'll give up. But I thought that PNG should be replacement to the GIF due to the patent issues with the GIF. It should have the same features and many more. And current browsers say that they support it. I think that this problem is in the PNG rendering engine of the browsers, but maybe there is some option in the PNG format which could tell the viewing program not to dither the image on the 24bit display. I'll try to search something on the problem on PNG format pages. Tom Mraz
Re: Bad rendering of PNG saved from GIMP
On Tue, Aug 01, 2000 at 02:19:53PM +0200, Tom Mraz [EMAIL PROTECTED] wrote: It's not problem of the indexed image. When you load the image into GIMP it is correct and the background color value is #f7e4ca as it should be and there is no dithering pattern. Tom, the images at the url you posted are _definitely_ patterned, regardless of the program you use to display them. As to bad support of png in browsers - I thought that MSIE 5.0 and latest Mozilla nightly should be correct, or not? Mostly correct in what they support, but neither supports transparency (AFAIK). -- -==- | ==-- _ | ---==---(_)__ __ __ Marc Lehmann +-- --==---/ / _ \/ // /\ \/ / [EMAIL PROTECTED] |e| -=/_/_//_/\_,_/ /_/\_\ XX11-RIPE --+ The choice of a GNU generation | |
Re : Bad rendering of PNG saved from GIMP
No, you can't. If the browser maps the same colours to different colours on screen at random it is broken. FALSE !!! You think as a computer but human body 'n' eyes can think the same bits of code are displayed meanwhile you have something different ... so slightly different bits can give eye perceived differences as a result. AFAIK PNG don't include transparent parameter ; GIF ought to be the best PNG does support transparency much better than GIF. In addition, browsers support GIF much better than PNG. Bad world. GIF is a standard ... using PNG is a form of anarchy Windoze is a standard ... using Linux ... Regards, Fabian
Re: Bad rendering of PNG saved from GIMP
Tom, the images at the url you posted are _definitely_ patterned, regardless of the program you use to display them. Yes, you are true, I'm stupid! Only the last image on the page is not patterned. But even the last image's background is displayed incorrectly in Mozilla and so. So the problem remains. Try to open the last image - the background color in gimp is #f7e4ca, but it renders in mozilla as #f6e2c5, but the background of the page is rendered as #f6e6cd. (Colors picked from screenshot). Why it's not the same? I understand that on 16bit display it had to find the nearest color, but why it does different rounding on the image and the page? Couldn't it be some problem of the gamma stored in the png image? Tomas Mraz
Re: Bad rendering of PNG saved from GIMP
do NOT use png's. they are are in general poorly supported by all web browsers. use .gif or .jpg. Please don't follow this advise. PNG's include a plenty of features like alpha-transparency, great interlacing and gamma information. Wherever you wan't to use a static GIF, PNG's can fit very well, since they support both indexed and realcolor depths. PNG uses a non-lossy compression so it's great for archival purposes too. GIF is a patent-bloated aging format that should disappear from the web. The problem of lacking browser support is not that hot, since number of v3 browsers is decreasing. Unfortunately only bleeding edge browsers (mozilla, gtkhtml, dunno about IW) support features like alpha-transparency, but you can safely live with 1bit mask as in GIF. For the problem addressed, JPEG is much worse, since the color information is stored using alossy compression formula and is always "similar" to the original color... PNG can give the same functionality of GIF as described later... Marc Lehmann also said: This is expected when you dither the image, so best do not convert your image to indexed format. There are two tricks when using indexed images: 1) Use 1bit transparency. Get rid the background color. If you don't want to dither to transparency or have rough edges, use the "semi-flatten" plugin. index and save as png. Even crappy NN4 should handle it. 2) get rid of the dithering: - use web safe pallette when indexing (crap results) - use web safe pallette color when working in RGB mode (for the bacground). Generate an optimized pallette in the second case, there might be problems with dithering, so either: - don't use dithering - select the bcg area using magic wand, index the image using dithering, fill the selection with the web safe color. Hope it helped Jakub Steiner -- -[ [EMAIL PROTECTED] ]-[ http://hideout.musichall.cz ]- "even a stopped clock gives a right time twice a day"
Re: Bad rendering of PNG saved from GIMP
Gamma correction? when I use some color for background of the image and the same color for the background of the HTML page and then I try to display the page in MSIE or Mozilla there is a slight difference in the background color
Re: Bad rendering of PNG saved from GIMP
Hi! then I try to display the page in MSIE or Mozilla there is a slight difference in the background color of the image and the background of the page. Is it some error in Gimp? Probably not, but how could I avoid it? I had similar problems with a web page some time ago. It's not Gimp's fault. I don't know if my solution is commonly used but it works and looks quite good. I've just made all areas filled with the background color transparent. The splash screen of my homepage is an example for this technique. Hope it helps! CU, Michael ---=[ [EMAIL PROTECTED] ]=--- ---=[ http://technoid.xodox.com ]=---
Re: Bad rendering of PNG saved from GIMP
ive read all the stuff on png support in web browsers. it sucks. every single browser out there has some kind of error. so basically, dont use pngs. ive read it and read it.
Re: Bad rendering of PNG saved from GIMP
Is it just me, or do interlaced png's take alot longer to load up that non-interlaced? I'm on a T3, so rendering is normally where the bottleneck is. I use Netscape 4.73 on linux, and it annoys me to the point where I don't do any interlacing at all on my web page graphics. Is this just a netscape thing?
Re: Bad rendering of PNG saved from GIMP
yes. i read all the W3C stuff.
Re: Bad rendering of PNG saved from GIMP
since I lost text-version ability Who says lynx doesn't support png's? Lynx actually does a much better rendering of png's than any `graphical' browser so far! Of course, it doesn't really do the rendering itself, but forks the displaying of it to xv or whatever the person installing lynx sets up as viewer for the images. (one could set that as the gimp, although that could get quite annoying loading up the gimp for each image one wants to see).
Re: Bad rendering of PNG saved from GIMP
Jakub Steiner wrote: The problem of lacking browser support is not that hot, since number of v3 browsers is decreasing. Unfortunately only bleeding edge browsers (mozilla, gtkhtml, dunno about IW) support features like alpha-transparency, but you can safely live with 1bit mask as in GIF. 'cuse the ignorance, but is it possible to create a png image that provides 'gif type of transparency?' That is, something that will work with current browsers and stay away from the patented gif format? As a developer inside the states and for a large corp., I can't accept the liability of using gimp to create gifs, yet I would love to create png images to replace existing transparent gifs. -- Until later: Geoffrey [EMAIL PROTECTED] Microsoft != Innovation
Re: Bad rendering of PNG saved from GIMP
Why would web brousers support png's if nobody is using them? Let's just start small by using the minimal features of png on our webpages, so that the web browsers will see that png is becoming popular and code in better support.
Re: Bad rendering of PNG saved from GIMP
hi, 'cuse the ignorance, but is it possible to create a png image that provides 'gif type of transparency?' That is, something that will work with current browsers and stay away from the patented gif format? yes, of course you can have PNGs with transparency RedHat Linxu comes with a transparentcy PNG for its login window with xdm/kdm (RedHat 6.1) the GIF format is only patented for its LZW compression technique... (so, get uncompressed GIFs and you can be free anyway ;-) alan
Re: Bad rendering of PNG saved from GIMP
Maybe I should clarify. I am aware that both gif and png provide transparency. My understanding is that (maybe the wrong terminology..) png transparency is a much finer resolution then that if gif. So the question is, is it possible to create a png image that uses the same transparency 'resolution' as a gif? Hope that makes sense. I've got little (any?) understanding of how transparency is implemented in either of these formats. Alan Buxey wrote: hi, 'cuse the ignorance, but is it possible to create a png image that provides 'gif type of transparency?' That is, something that will work with current browsers and stay away from the patented gif format? yes, of course you can have PNGs with transparency RedHat Linxu comes with a transparentcy PNG for its login window with xdm/kdm (RedHat 6.1) the GIF format is only patented for its LZW compression technique... (so, get uncompressed GIFs and you can be free anyway ;-) alan -- Until later: Geoffrey [EMAIL PROTECTED] Microsoft != Innovation
Re: Bad rendering of PNG saved from GIMP
hi, ive read all the stuff on png support in web browsers. it sucks. every single browser out there has some kind of error. so basically, dont use pngs. ive read it and read it. ...and I supposed these people tested all the browsers out there, yes? I mean, after all, theres Netscape, IE, Voyager, Opera, IBrowse, Hotjava, Mozilla, I-Spy, Arena, StarOffice, KDEs Browser, etc etc alan
Re: Bad rendering of PNG saved from GIMP
hi, Why would web brousers support png's if nobody is using them? Let's just start small by using the minimal features of png on our webpages, so that the web browsers will see that png is becoming popular and code in better support. my favourite browsers supported PNG since last year. as soon as they did I converted all my images to PNG. saved 2Mb of web space (with high quality images) and thought 'who cares' about the older web-browser based people. after all, since I lost text-version ability, I've added all other bits to the site that NEED post-3rd generation browsers anyway! :-) alan
Re: Bad rendering of PNG saved from GIMP
hi, On Tue, 1 Aug 2000, James Smaby wrote: since I lost text-version ability Who says lynx doesn't support png's? Lynx actually does a much better rendering of png's than any `graphical' browser so far! Of course, it doesn't really do the rendering itself, but forks the displaying of it to xv or whatever the person installing lynx sets up as viewer for the images. (one could set that as the gimp, although that could get quite annoying loading up the gimp for each image one wants to see). okay 'inlined viewing ability' then :-) by text-version I mean a version that has all data as text (no imagemaps etc etc) so that it can be used by blind people surfing. I still have this on some of my pagesits a nice and neat thing to do. alan
Re: Bad rendering of PNG saved from GIMP
Hello everybody, It is very stimulating to hear an alive list. I use pngs not because of rendering concepts (I am not a graphics pro), but because I like to belong to a family that is eager to share. The best things (graphically speaking) of the two pages I have worked on, were made firstly by hand (my six and a half years old son´s drawing in http://www.crosswinds.net/~ggce/index.html) and with MS powerpoint (http://www.crosswinds.net/~educamus/index.html). However important the rendering might be, one has to consider also the media in which the graphic work is being published. I think that internet is a mixed media in that sense, and textuality is an important part of the whole value (no painter paints for the blind people, but blind people need to access pages with graphics too). If we encompass all the points of view, we can still enjoy with both senses (rendering and textuality) funny stories like this one heard in a Houston, Texas airport bar: "One mature lady fell in love with a youger guy with big muscles and a tatoo fan himself. After some time of evergrowing romance, the lady decided to give her lover a very meaningful birthday present. The day of the birthday, she went in a rush to a tatoo parlor (?) almost at closing time to get a low budgeted and sexy tatoo in both her buttocks. Could she have some butterflies for 20 dls ? No, said the man of the parlor, the butterflies would take more time than the time left before I close, and, much more money. Ok, said the lady, would you be able to put a couple of bees, one in each buttock, it is a very special present, please. Ok, said the man, that is just in time and budget. The man made the tattoo, the lady went home and put her pants down and showing her buttocks to her boyfriend and touching the floor with her hands exclaimed Happy birthday !!. The boyfriend yelled with anger: Who the hell is BoB ?" Maybe a brighter future is one with all the tools included (one day even the blind people will enjoy all your beautiful works), and lists as good as this. Thanks to everybody. Gerardo García C. Tampico, Tamps. México From: Rebecca Jean Pedersen [EMAIL PROTECTED] To: Alan Buxey [EMAIL PROTECTED] CC: Tom Mraz [EMAIL PROTECTED], [EMAIL PROTECTED] Subject: Re: Bad rendering of PNG saved from GIMP Date: Tue, 01 Aug 2000 16:11:48 +0200 ive read all the stuff on png support in web browsers. it sucks. every single browser out there has some kind of error. so basically, dont use pngs. ive read it and read it. Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com
