Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Xls/Escher.php
private function readBlipJPEG()
    {
        // offset: 0; size: 2; recVer and recInstance

        // bit: 4-15; mask: 0xFFF0; recInstance
        $recInstance = (0xFFF0 & Xls::getUInt2d($this->data, $this->pos)) >> 4;

        $length = Xls::getInt4d($this->data, $this->pos + 4);
        $recordData = substr($this->data, $this->pos + 8, $length);

        // move stream pointer to next record
        $this->pos += 8 + $length;

        $pos = 0;

        // offset: 0; size: 16; rgbUid1 (MD4 digest of)
        $rgbUid1 = substr($recordData, 0, 16);
        $pos += 16;

        // offset: 16; size: 16; rgbUid2 (MD4 digest), only if $recInstance = 0x46B or 0x6E3
        if (in_array($recInstance, [0x046B, 0x06E3])) {
            $rgbUid2 = substr($recordData, 16, 16);
            $pos += 16;
        }

        // offset: var; size: 1; tag
        $tag = ord($recordData[$pos]);
        $pos += 1;

        // offset: var; size: var; the raw image data
        $data = substr($recordData, $pos);

        $blip = new Blip();
        $blip->setData($data);

        $this->object->setBlip($blip);
    }
private function readBlipJPEG()
    {
        // offset: 0; size: 2; recVer and recInstance

        // bit: 4-15; mask: 0xFFF0; recInstance
        $recInstance = (0xFFF0 & Xls::getUInt2d($this->data, $this->pos)) >> 4;

        $length = Xls::getInt4d($this->data, $this->pos + 4);
        $recordData = substr($this->data, $this->pos + 8, $length);

        // move stream pointer to next record
        $this->pos += 8 + $length;

        $pos = 0;

        // offset: 0; size: 16; rgbUid1 (MD4 digest of)
        $rgbUid1 = substr($recordData, 0, 16);
        $pos += 16;

        // offset: 16; size: 16; rgbUid2 (MD4 digest), only if $recInstance = 0x46B or 0x6E3
        if (in_array($recInstance, [0x046B, 0x06E3])) {
            $rgbUid2 = substr($recordData, 16, 16);
            $pos += 16;
        }

        // offset: var; size: 1; tag
        $tag = ord($recordData[$pos]);
        $pos += 1;

        // offset: var; size: var; the raw image data
        $data = substr($recordData, $pos);

        $blip = new Blip();
        $blip->setData($data);

        $this->object->setBlip($blip);
    }
Read BlipJPEG record. Holds raw JPEG image data.