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"In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

  • 1.  "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-20-2024 11:51 PM

    1.I scanned the gravure print and used the Curve4 software to obtain tone curve adjustment values ranging from 0 to 100.

    2.However, the cylinder plating company uses curve values ranging from 0 to 255. Therefore, to adjust the cylinder curves, they require curve values that can be applied in the HelioDisk software.

    3.I tried simply converting the values from 0–100 to 0–255, but the results were incorrect.

    4.Can I determine the curve values suitable for HelioDisk using the print materials I have, along with i1Pro and Curve4 software?



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    Lee-Seul Choi
    UWRAPCO
    82-10-7159-6971
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  • 2.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-21-2024 02:16 PM
    Hi.

    This may or may not help, but, after a bit of digging, I see that if you export the grayscale curves in the Curve software using the Konica Minolta XML format, the values are exported in a 0-255 range.

    Then the next question would be what specific format is required for the platemaking RIP at the printing site (it may not be XML).

    Regards.

    Marco Ugolini
    Color and Print Specialist
    Certified G7© Expert





  • 3.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-22-2024 12:17 AM

    The Konica Minolta XML format appears to be a simple conversion of values ​​from 1 to 100 to values ​​from 0 to 255, and cylinder engraving companies say that this value does not match gravure cylinders. We only carry out gravure printing, and request gravure cylinder engraving to a professional company. Gravure plate makers are said to use a RIP called "HelioDisk".



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    Lee-Seul Choi
    UWRAPCO
    82-10-7159-6971
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  • 4.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-23-2024 10:21 AM

    I am not sure but maybe a simple conversion table could work



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    Dorel Dabija
    Navitor Midwest
    Mankato MN
    (507) 304-6300
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  • 5.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-23-2024 11:53 AM
    Edited by Wojciech Bialkowski 07-23-2024 01:38 PM

    I think your problem is that you provide them with data for a ready-made correction curve.


    1) The first question is whether you assigned the curve from the heliodisk as Initial Curve in Curve4 in decimal encoding. 

    I think you're working on a linear curve though. And that's why there are problems with the results obtained despite conversion to 8 bit.

    Your initial decimal curve should be something like this (based on the data from the screenshot).

    and then the result should look something like this

    and you have to recalculate it to 8 bit.

    2) If you are working on a linear curve, you can use the difference values ​​(delta +/-) by converting to 8 bits. Then add or subtract these values ​​for the curve in heliodisk.

    The measurement data is random to visualize what we have to do and the output curve is an example.



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    Wojciech Bialkowski G7 Expert
    Studio Omega
    Bydgoszcz
    Poland
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  • 6.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-23-2024 11:58 AM
      |   view attached

    Ready file for Curve4 Initial Curve



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    Wojciech Bialkowski G7 Expert
    Studio Omega
    Bydgoszcz
    Poland
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    Attachment(s)



  • 7.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-23-2024 02:45 PM

    As for companies that engrave cylinders, they are very conservative. Because their tools are from a "previous era".

    I suggest you do not make any changes to the curve in HelioDisk and add an intermediate stage.

    Take the finished Repro PDF file and perform the separation using the DEVICE LINK profile generated in Curve4 with Linear selected as the base curve.

    Similarly, you can also add curves to a ready-made 8 bit TIFF file, e.g. in Photoshop, using correction layers with the curve from the .acv file generated in Curve4.



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    Wojciech Bialkowski G7 Expert
    Studio Omega
    Bydgoszcz
    Poland
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  • 8.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-24-2024 04:04 AM

    Thank you for your response.

    1. I don't know the HelioDisk curve values that were applied to the Initial cylinder. The gravure cylinder manufacturer said that it could not provide the applied curve value, and the photo below will be provided simply as a reference for the HeliDisk curve value format.
    2. So, after scanning the printed material, I have to estimate the previously applied HelioDisk curve value with the tone value from 1 to 100 (curve value + delta value) obtained from curve4.
    3. The gravure cylinder manufacturer said that they would modify the cylinder themselves using the tone values ​​from 1 to 100 obtained from curve4 and send it to them. But I want to go as far as trying it myself.


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    Lee-Seul Choi
    UWRAPCO
    82-10-7159-6971
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  • 9.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-24-2024 06:14 AM
    Edited by Wojciech Bialkowski 07-24-2024 12:39 PM
      |   view attached

    Step by step procedure.

    1) Select Run 1 - Calibration in the Runs window
    2) Select Based On: Linear (none)

    3) Make a measurement, preferably several, e.g. P2P51characteristics, or load the measurements.
    4) Set the G7 calibration parameters - Printing Aims, White/Black Gray Balance.

    then:

    5) Select 8bit_Decimal_List (attached to the post).
    6) Select Delta
    7) Export as CGATS

    8) In Excel, convert Decimal to 8bit with rounding to intiger.

    Formula for column IN 'Sample_Name': (100 - decimalIN) x 2.55

    Formula for Delta Value: decimalDelta / (100/255)

    Delta data has positive and negative values, therefore a different formula keeping positive or negative values.

    You can hide the % columns and specify only 8 bit for the convenience of engraving shop operators. Of course, send him the Excel file and then he can enter "his secret OUT" data into the table and immediately calculate the new value.


    9) Send the data to the engraving shop. Since we do not know which bits are used as IN in HelioDisk, they must read the correction value for a specific IN bit from the sent table.

    Important! In this case of an unknown curve, always follow the procedure given above, even if it is the next iteration.



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    Wojciech Bialkowski G7 Expert
    Studio Omega
    Bydgoszcz
    Poland
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    Attachment(s)

    txt
    8bit_Decimal_List.txt   8 KB 1 version


  • 10.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-26-2024 03:09 AM

    Thank you for your reply.

    I have modified the data according to your advice and forwarded it to the cylinder manufacturer.

    The cylinder manufacturer said that the numbers were ridiculous and that they would rather correct them and send them to me, but I want to check the printed version to see how ridiculous it is, so I am currently correcting the cylinder.

    I will write again once the printing is completed with the revised cylinder.

    *For reference, the flexo printer is also performing G7 at the same time (the resin plate is also commissioned to a specialized manufacturer), and unlike the gravure printing, it is progressing in a positive direction without any blocking due to the resin plate curve value.



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    Lee-Seul Choi
    UWRAPCO
    82-10-7159-6971
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  • 11.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-26-2024 03:38 AM

    Your OUT (Delta) data looks like decimal percentage values. However, if these are 8-bit values, you should round them to integers.

    By the way, your case is similar to those I have encountered in cooperation with engraving companies in Europe. My company produces polymer plates for flexo printing as a supplier and most of them are in G7 calibration. However, when everything is clarified with the engraving company on the G7 topic - you will see how stable these curves are in rotogravure printing.



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    Wojciech Bialkowski G7 Expert
    Studio Omega
    Bydgoszcz
    Poland
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  • 12.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 07-27-2024 08:15 AM
    Artworks software had a tag that could be added to the file, in 0-100% format that the Hellio can read.

    I believe Esko and Hybrid do also.

    Steve

    Steve Smiley
    SmileyColor & Associates
    PO BOX 1015
    Bacliff TX, 77518 USA
    469-309-2025
    Steve@...




  • 13.  RE: "In gravure printing, how are the curve values from 0 to 255 obtained when applying them using the HelioDisk software for the cylinder?"

    Posted 08-20-2024 10:24 AM

    gravure printing, HelioDisk software precisely calculates curve values from 0 to 255 by converting tonal information into engraving depths on the cylinder. This ensures accurate ink transfer, resulting in high-quality prints with smooth gradients and sharp details.



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    Sophia Gary
    Open Buisness Club GbmH
    Hamburg
    49-40-419-131-30
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