Re: [Gimp-user] How to Combine Layers with Feathered or Softened Edges
John Culleton wrote: On Tuesday 21 July 2009 01:58:33 pm James Cobban wrote: I am trying to combine images scanned from microfilm in the case where the lens on the microfilm scanner is too powerful to permit me to scan an entire page into a single image file. I believe that this application is similar to trying to create a landscape from multiple photographs. This is described well in "The Artist's Guide to Gimp Effects", page 47. Basically it involves applying a gradient to a layer mask. Thank you. As is often the case with documentation, the trick is learning what words the documentation uses to describe a feature. -- Jim Cobban jamescob...@sympatico.ca 34 Palomino Dr. Kanata, ON, CANADA K2M 1M1 +1-613-592-9438 ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
[Gimp-user] How to Combine Layers with Feathered or Softened Edges
I am trying to combine images scanned from microfilm in the case where the lens on the microfilm scanner is too powerful to permit me to scan an entire page into a single image file. I believe that this application is similar to trying to create a landscape from multiple photographs. I scan the original into a PDF containing multiple images. I then open this PDF as layers. I have been able to rearrange the layers, raise and lower them, and merge them to create a single image file, but I have 2 problems: 1) Sometime the key spots within the layers which I need to line up prior to merging the layers are not right on the edge of either layer. To perform the alignment I need to make at least the outer portion of the upper layer partially transparent so I can properly align them. 2) Once I am finished the contrast between the two layers is generally such that the edge of the upper layer is clearly visible in the merged result. Once again if I could make the outer edge of the upper layer transparent on a gradient to fully transparent at the edge, I could make the edge invisible. I think of this operation as feathering the layer, but searching through the documentation and web guides I can only find feathering as applicable to images, not layers. The following is an example of the result I currently have: http://www.jamescobban.net/Ontario/images/B1912_33007.jpg Combined image from microfilm. -- View this message in context: http://www.nabble.com/How-to-Combine-Layers-with-Feathered-or-Softened-Edges-tp24592342p24592342.html Sent from the Gimp User mailing list archive at Nabble.com. ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
[Gimp-user] Large file size on TIFF to JPEG conversion
I scanned some microfilm yesterday. For some reason the software does not support JPEG so I scanned into TIFF format, putting 5 images in each TIFF file to reduce the number of times I had to enter a file name. When I got home I used GIMP to extract the individual images into JPEGs. Unexpectedly the JPEGs are enormous! For example one of the TIFF files that was 5MB in total, containing 5 images remember, exported into JPEGs which ranged from 9.0MB to 9.6MB! That is using the default 85% quality. This is unexpected since TIFF uses lossless compression while I have indicated to GIMP that I would tolerate some quality loss. Even when I reduced the quality to 65% the JPEGs were still over 5MB each. Are there any suggestions on how I can get GIMP to construct reasonable sized JPEGs? -- View this message in context: http://www.nabble.com/Large-file-size-on-TIFF-to-JPEG-conversion-tp23794145p23794145.html Sent from the Gimp User mailing list archive at Nabble.com. ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] Large file size on TIFF to JPEG conversion
Leonard Evens wrote: On Sat, 2009-05-30 at 08:00 -0700, James Cobban wrote: I scanned some microfilm yesterday. For some reason the software does not support JPEG so I scanned into TIFF format, putting 5 images in each TIFF file to reduce the number of times I had to enter a file name. When I got home I used GIMP to extract the individual images into JPEGs. Unexpectedly the JPEGs are enormous! For example one of the TIFF files that was 5MB in total, containing 5 images remember, exported into JPEGs which ranged from 9.0MB to 9.6MB! That is using the default 85% quality. This is unexpected since TIFF uses lossless compression while I have indicated to GIMP that I would tolerate some quality loss. Even when I reduced the quality to 65% the JPEGs were still over 5MB each. Are there any suggestions on how I can get GIMP to construct reasonable sized JPEGs? There may be some obvious answer o your question I don't know about. I hope someone provides it. But... It is hard to evaluate your question without knowing some more about the images. What size was the original tiff file? The original TIFF file was 5.0MB, as I stated in my post. That was the total for 5 images, indicating that each individual image within the TIFF file was about 1MB. What were the pixel dimensions of the individual subimages which you wanted to save as jpegs? 5088x3096 pixels. This is the same size reported by Image Viewer for both the first image in the TIFF file and the extracted JPEG. The microfilm scanner treats the image as if it was an 11x17" document being scanned at 300dpi. What size would they be if you saved them as tiff files? Among other things, jpeg only compresses significantly if there is sufficient redundancy in the file to do so. If that isn't so, it is conceivable you might not get that much reduction. How about showing us one of those images? The original image is a scan of a page from a census. So there should be enormous redundancy in the image. In any event TIFF is able to compress each image to about 1MB using lossless compression, so clearly JPEG should be able to do better. GIMP reports that it takes 75MB to hold the image inside the editor! I have continued experimenting. At quality 3 (3!) and smoothing .85 the JPEG is 604KB and still fairly easy to read. I have put that last version up at http://www3.sympatico.ca/jamescobban/1871_Middlesex_WilliamsW_B3_056.jpg as a demonstration. The quality is acceptable; most of the remaining problems with the image are either due to the poor quality of the original microfilm (the vertical striations) or problems with the scanner (the horizontal striations). I am just astonished that I have to set such extreme quality values to get a reasonable sized file. -- Jim Cobban jamescob...@sympatico.ca 34 Palomino Dr. Kanata, ON, CANADA K2M 1M1 +1-613-592-9438 ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
Re: [Gimp-user] Large file size on TIFF to JPEG conversion
John Coppens wrote: On Sat, 30 May 2009 08:00:05 -0700 (PDT) James Cobban jamescob...@sympatico.ca wrote: When I got home I used GIMP to extract the individual images into JPEGs. Unexpectedly the JPEGs are enormous! For example one of the TIFF files that was 5MB in total, containing 5 images remember, exported into JPEGs which ranged from 9.0MB to 9.6MB! That is using the default 85% quality. Note that in some cases, lossless compression can give you much better results than jpg. Particularly if the original is a complicated line drawing (high contrast). Also, if the original is using indexed colors, it may be more efficient. And if the original is a b/w 1 bit/pixel image, even more so. Try to convert to PNG or GIF and check if those formats give you more logical sizes - they work better with the mentioned image types. John Thank you to everyone for all the input. This has been a useful learning experience. -- Jim Cobban jamescob...@sympatico.ca 34 Palomino Dr. Kanata, ON, CANADA K2M 1M1 +1-613-592-9438 ___ Gimp-user mailing list Gimp-user@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-user
