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MS Office Forum / Excel / Printing / June 2005Why do raster images get dirty white areas?
Logotypes in raster formats get dots in white areas like backgrounds when printed on laser printers etc. As far as I have tested this applies to png, tif,bmpformats and presumably other raster formats. Is there any work-around other than transparent whites which Adobes pdf-makers won't accept except in the very latest versions. Is this really an Excel question looks like you are using an Adobe product. If you convert from curves to bitmap, I'd expect you would want the image to be created in exactly the same size as you will be using the image, with the same dots per inch as your printing, and that would eliminate forcing the pages tall and/or pages wide (if this really is Excel). .. --- HTH, David McRitchie, Microsoft MVP - Excel [site changed Nov. 2001] My Excel Pages: http://www.mvps.org/dmcritchie/excel/excel.htm Search Page: http://www.mvps.org/dmcritchie/excel/search.htm > Logotypes in raster formats get dots in white areas like backgrounds when > printed on laser printers etc. As far as I have tested this applies to png, > tif,bmpformats and presumably other raster formats. > > Is there any work-around other than transparent whites which Adobes > pdf-makers won't accept except in the very latest versions. Logotypes are created in png-format in PS-Pro och CorelDraw. Raster logotypes are always produced in exact final dimensions and 600 dpi to suit most printers and are inserted in Excel at 100%. If smaller logotypes are required for following pages they are created anew in correct size. (Earlier we used transparent backgrounds but as I said Adobes PDF-maker can't manage transparencies.) This is definitely an Excel problem because people from National and Regional Government departments, Major commercial Groups and Political parties love to use Excel for charts and tables carrying their logotypes. Is there any work around? > Is this really an Excel question looks like you are using an Adobe > product. [quoted text clipped - 16 lines] > > Is there any work-around other than transparent whites which Adobes > > pdf-makers won't accept except in the very latest versions. The only workaround would be to manually retouch the files, which is something you would normally do after scanning anyway. Converting from curves to dots is similar to scanning you are not going to get exactly the results you want. Do you perhaps have options to throw away black pixels completely surrounded by white. What about .gif files they've been around a long time, surely they are acceptable to most software (on PC's) From CoralDraw you can create them in any format or are you not the creating entity. High speed printers used to print at 280 dpi (or was it 240) probably higher now, but you are certainly going to have different resolutions and that is why as you know curves work better and are generally smaller.. -- HTH, David McRitchie, Microsoft MVP - Excel [site changed Nov. 2001] My Excel Pages: http://www.mvps.org/dmcritchie/excel/excel.htm Search Page: http://www.mvps.org/dmcritchie/excel/search.htm > Logotypes are created in png-format in PS-Pro och CorelDraw. Raster logotypes > are always produced in exact final dimensions and 600 dpi to suit most [quoted text clipped - 29 lines] > > > Is there any work-around other than transparent whites which Adobes > > > pdf-makers won't accept except in the very latest versions. There are no dots in the graphic file on the white areas. I can check this in Photoshop. If I insert the file into Word or PowerPoint there will be no dots in the print-outs. When I print from Excel there are dots. The logotypes are used throughout extensive organisations with many different combinations of Office and Windows versions. Similarily there is a wide gamut of printers and printer resolutions. It seems that the trouble has something to do with how pixels are re-sized in Excel compared to the other Office applications. I think one can even get dots on screen images in certain zooms but not in others. If I understand rightly you mean that the raster image should be generated in accordance with the lpi range of the printer rather than its dpi. This would mean resolutions of 110 to 300 dpi instead of the 600 dpi we have been using. Logotypes are generally -- but not always -- line drawings and use house colors of exact formulation. Do you think we should change our resolution approach? > The only workaround would be to manually retouch the files, which is > something you would normally do after scanning anyway. [quoted text clipped - 50 lines] > > > > Is there any work-around other than transparent whites which Adobes > > > > pdf-makers won't accept except in the very latest versions. You would have to blow up the picture very large to see it on the screen don't know if the screen resolution is 72 dpi or what but you are going to have to blow it up to something like 1000%. and not really be guaranteed that you will see a problem. I don't think lpi has anything to do with printer problems unless you're printing on a dot matrix printer and change the lpi to other than the preferred setting. I was talking strictly dpi. HTH, David McRitchie, Microsoft MVP - Excel [site changed Nov. 2001] My Excel Pages: http://www.mvps.org/dmcritchie/excel/excel.htm Search Page: http://www.mvps.org/dmcritchie/excel/search.htm > There are no dots in the graphic file on the white areas. I can check this in > Photoshop. If I insert the file into Word or PowerPoint there will be no dots [quoted text clipped - 69 lines] > > > > > Is there any work-around other than transparent whites which Adobes > > > > > pdf-makers won't accept except in the very latest versions. My screen applications allow zooming up to 5000 and I can check that the color is 255+255+255. You sent me to article 320314 which recommends lpi 55-85 for lasers, 50 - 60 for ink-jets and 300 for imagesetters. There are other recommendations (CorelDraw 12) for 150 dpi png transparents for desktop printing in Office applications (this would be suitable for all but imagesetters). I will test these and let you know the results. > You would have to blow up the picture very large to see it on the screen > don't know if the screen resolution is 72 dpi or what but you are going [quoted text clipped - 83 lines] > > > > > > Is there any work-around other than transparent whites which Adobes > > > > > > pdf-makers won't accept except in the very latest versions. OK, now I have tested and the results are inconsisent. One logotype at 600 dpi had dirty white as did one at 150 dpi. One at 600 dpi was clean. All had exactly 100% size and printing was on a laserjet 4000 using pcl 5. Copying the images from Excel into a graphic program and zooming to 5000% does not show any unwanted dark pixels. I am lost. Thanks for trying. > My screen applications allow zooming up to 5000 and I can check that the > color is 255+255+255. You sent me to article 320314 which recommends lpi [quoted text clipped - 90 lines] > > > > > > > Is there any work-around other than transparent whites which Adobes > > > > > > > pdf-makers won't accept except in the very latest versions. The article you mentioned did not come, from this thread, but it was interesting. Description of the guidelines for selecting the appropriate picture format in an Office XP program http://support.microsoft.com/kb/320314 So I see that GIF files are raster not vector, and should have been using the word vector instead of curves for drawn files.. When I was concerned with this stuff, on the PC side we had a PostScript printer for testing, and a PC printer with AFP software drivers to simulate high speed AFP printing (mainframes). But I don't see a format with drawn curves (vector) that applies to PC printers, the vector formats are for the graphics programs themselves. . Anyway when a raster picture gets rescaled you are not going to get the same picture, close but not the same, it is going to have to add or remove pixels. So for a logo you would want to make sure you have the result for the exact usage, if possible. Lots of experimenting. The lpi in something different than 6 or 8 lpi for characters. Wonder what they are measuring -- distinctiive black lines I would suppose. --- HTH David McRitchie, Microsoft MVP - Excel [site changed Nov. 2001] My Excel Pages: http://www.mvps.org/dmcritchie/excel/excel.htm Search Page: http://www.mvps.org/dmcritchie/excel/search.htm > OK, now I have tested and the results are inconsisent. One logotype at 600 > dpi had dirty white as did one at 150 dpi. One at 600 dpi was clean. All had [quoted text clipped - 97 lines] > > > > > > > > Is there any work-around other than transparent whites which Adobes > > > > > > > > pdf-makers won't accept except in the very latest versions. |
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