doc:appunti:hardware:canoscan_9000f_mark_ii
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doc:appunti:hardware:canoscan_9000f_mark_ii [2014/11/18 21:29] – [Invert and color balance] niccolo | doc:appunti:hardware:canoscan_9000f_mark_ii [2017/12/04 10:00] – [ImageMagick convert, memory issue] niccolo | ||
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We choose by visual inspection the best value for gamma; 0.007 in this example. | We choose by visual inspection the best value for gamma; 0.007 in this example. | ||
- | Then we open with Gimp a sample photo, we need a shot with good **black**, **gray** and **white** spots. The process is: | + | Thake a film strip (negated and gamma-corrected with the above recipe) and open it with the Gimp. We need a strip with good **black**, **gray** and **white** spots. The process is: |
- Apply a **pixelize blur filter** on the black, gray and white spots. Make it large enough so you can easly pick the color from it in the next steps. | - Apply a **pixelize blur filter** on the black, gray and white spots. Make it large enough so you can easly pick the color from it in the next steps. | ||
- Open menu **// | - Open menu **// | ||
- From **//All Channels// | - From **//All Channels// | ||
- | - From //Channel// select //Red//, click **//Pick black point//** and click on the black spot. Click **//Pick white point//** and click on the white spot. | + | - From **//Channel//** select |
- Repeat the above step for **// | - Repeat the above step for **// | ||
- | - Annotate | + | - Before closing |
- | Suppose that the values | + | Suppose that the values are: |
- | | Red | 22 | 1.06 | 193 | | + | ^ Channel |
- | | Green | 20 | 1.01 | 190 | | + | | Red | |
- | | Blue | + | | Green | |
+ | | Blue | ||
The black and white points are integers 0-255, we need to convert it into a percent value; e.g. for the red white point: 22 / 255 * 100 = 8.63%. | The black and white points are integers 0-255, we need to convert it into a percent value; e.g. for the red white point: 22 / 255 * 100 = 8.63%. | ||
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- Repeat the last two steps. | - Repeat the last two steps. | ||
+ | |||
+ | ===== ImageMagick convert, memory issue ===== | ||
+ | |||
+ | Executing **convert** on very large images can lead to memory exhausted issue. I experienced it converting a TIF scan into PNG (because I wish to avoid 24 bit Gimp limitation with TIF images): | ||
+ | |||
+ | < | ||
+ | convert very-big.tif very-big.png | ||
+ | convert-im6.q16: | ||
+ | convert-im6.q16: | ||
+ | convert-im6.q16: | ||
+ | </ | ||
+ | |||
+ | It seems that ImageMagick is self-limiting the disk resource it will use, you can fix the configuration file **''/ | ||
+ | |||
+ | <code xml> | ||
+ | < | ||
+ | <policy domain=" | ||
+ | <policy domain=" | ||
+ | <policy domain=" | ||
+ | <policy domain=" | ||
+ | <policy domain=" | ||
+ | <policy domain=" | ||
+ | </ | ||
+ | </ | ||
+ | |||
+ | May be you can also increase the Memory resource, if you have enough: | ||
+ | |||
+ | < | ||
+ | convert -list resource | ||
+ | Resource limits: | ||
+ | Width: 16KP | ||
+ | Height: 16KP | ||
+ | Area: 128MP | ||
+ | Memory: 256MiB | ||
+ | Map: 512MiB | ||
+ | Disk: 1GiB | ||
+ | File: 768 | ||
+ | Thread: 2 | ||
+ | Throttle: 0 | ||
+ | Time: unlimited | ||
+ | </ | ||
===== Web references ===== | ===== Web references ===== |
doc/appunti/hardware/canoscan_9000f_mark_ii.txt · Last modified: 2019/12/23 09:36 by niccolo