Search found 457 matches

by GreenKoopa
2013-08-19T15:57:13-07:00
Forum: Users
Topic: Progressive jpg
Replies: 5
Views: 8533

Re: Progressive jpg

ImageMagick is great at image processing. It has many options when writing JPEGs . If your command is the last step of a longer process, fmw42's advice is perfect. But if you are only modifying jpeg attributes such as the coding, a jpeg specific tool, such as jpegtran , will work faster and with zer...
by GreenKoopa
2013-08-19T07:33:21-07:00
Forum: Users
Topic: compare images with tolerance
Replies: 3
Views: 6421

Re: compare images with tolerance

Welcome. Also see http://imagemagick.org/script/compare.php Is AE the metric you want? Are only regions of your image changing? Is the image format lossless? Is a slightly brightened image 100% different? AE = absolute error count, number of different pixels (-fuzz effected) Or do you have your meth...
by GreenKoopa
2013-08-19T07:21:49-07:00
Forum: Users
Topic: [[SOLVED]] Count pixels with distinct neighborhood
Replies: 11
Views: 5042

Re: Count pixels with distinct neighborhood

Welcome. Morphology is a neighborhood operator. http://www.imagemagick.org/Usage/morphology/ Can you provide an example image and give any constraints that may help? "binary black-and-white image" helps clarify. Does perimeter mean that you always have a single, solid, black shape on a white backgro...
by GreenKoopa
2013-08-17T19:04:54-07:00
Forum: Users
Topic: Reversed Bilinear Distortion + Crop
Replies: 4
Views: 3315

Re: Reversed Bilinear Distortion + Crop

etb972 wrote:the problem is that my image is not croped.. and has not the good size !
I'm not clear on your meaning. Do you know about the viewport setting of -distort ?
by GreenKoopa
2013-08-16T23:41:21-07:00
Forum: Users
Topic: Removing complex vighetting
Replies: 7
Views: 5108

Re: Removing complex vighetting

fx expects expression in double quotes, while the examples use single quotes. My platform is Windows, which is the reason for the above. I don't think IM or fx care, but it does want one parameter. Windows breaks at spaces unless inside double quotes. Most examples need to be converted for Windows....
by GreenKoopa
2013-08-16T14:23:02-07:00
Forum: Users
Topic: Removing complex vighetting
Replies: 7
Views: 5108

Re: Removing complex vighetting

-fx "u+v.p{w/2,h/2}-v" That puts a lot of weight on an individual pixel. Make sure the center one is a good one. It might help to blur ColorVign.tif slightly. HDRI is best. An alternative is to de-contrast using +level, do your correction, then re-contrast. -auto-level is ideal , but play with othe...
by GreenKoopa
2013-08-16T07:35:06-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 31499

Re: From sRGB to CMYK and gamma?

joew wrote:Printing from gimp is exactly what I want to avoid.
My mistake. I don't print using Gimp because it frequently gets the position wrong, but maybe this is an incompatibility with my very old printer. How are you printing?
by GreenKoopa
2013-08-16T07:25:31-07:00
Forum: Digital Image Processing
Topic: Fuzz culculator
Replies: 21
Views: 31807

Re: Fuzz culculator

u and v are the two images (pixels/colors) being compared. .r, .g, .b are the three channels. Red, green, blue for RGB. Or, somewhat confusingly, Lightness, a, b for Lab. Or hue, saturation, value for HSV. Etc. I found lab is more precise than RGB. Lab matches human perception better. But which colo...
by GreenKoopa
2013-08-15T09:25:10-07:00
Forum: Digital Image Processing
Topic: Fuzz culculator
Replies: 21
Views: 31807

Re: Fuzz culculator

IM does have -fuzz, but it is only one method of calculating such things and may not be what you want. It will be affected by your -colorspace.

Source code is available:
http://www.imagemagick.org/script/install-source.php
by GreenKoopa
2013-08-15T09:17:57-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 31499

Re: From sRGB to CMYK and gamma?

You can print from Gimp and still let your printer driver handle the colorspace and sampling conversions.

You know your image's size in pixels, and you know what you want it printed in inches. Divide and set density (pixels per inch).
by GreenKoopa
2013-08-15T09:13:24-07:00
Forum: Users
Topic: How to widen transparency?
Replies: 8
Views: 5226

Re: How to widen transparency?

You want all lines and shapes thinned? Morphology is one option.
http://www.imagemagick.org/Usage/morphology/

The aliasing of your lines may add a step of complexity.
by GreenKoopa
2013-08-15T08:49:37-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 31499

Re: From sRGB to CMYK and gamma?

I would let your printer do the sRGB to CMYK conversion unless you have a reason for doing otherwise. I would also let your printer do the -resample/-resize unless you have a reason. Use -density to set the print size.
by GreenKoopa
2013-08-15T07:40:57-07:00
Forum: Digital Image Processing
Topic: Fuzz culculator
Replies: 21
Views: 31807

Re: Fuzz culculator

I second the suggestion to read up on colorspaces. This is a huge topic we couldn't do justice to here. There are no simple answers, so be prepared to commit some time and learn a lot. I realized that it is something completely different to calculate colors on real world painting than we do in IT wo...
by GreenKoopa
2013-08-15T07:18:11-07:00
Forum: Users
Topic: From sRGB to CMYK and gamma?
Replies: 48
Views: 31499

Re: From sRGB to CMYK and gamma?

I figured, I should use the "-colorspace XXX" options instead of directly fiddling with gamma. Can anybody confirm this assumption? I would use -colorspace RGB and -colorspace sRGB above, especially since the sRGB gamma isn't quite 2.2 (or even constant). However, the improvement will be small. If ...
by GreenKoopa
2013-08-13T17:51:02-07:00
Forum: Users
Topic: how -trim images with black border and black background
Replies: 17
Views: 18754

Re: how -trim images with black border and black background

"Best I can suggest is do it twice, once with -trim and once with -shave. Then chose the larger of the two output images." But GreenKoopa's solution will produce the same result. I'm not sure that they are always the same. Each of the four sides may be trimmed more or less than the shave. What exac...